Care and Feeding of the Windows Registry

The Registry is the essential part of Windows - a big, complex database that stores all the configuration settings for your software and hardware in a hierarchical form like file folders. You don't often need to deal with the Registry, because Windows' built-in tools work in the background to make sure it stays in tip-top shape. But because the Registry is so huge and complicated, it can develop troubles that cause strange problems or even bring your PC to a grinding halt.

To most of us, the Windows Registry is a dark and mysterious place. This month, we cover some basic housekeeping chores you can do to keep the Registry happy, and we review some Windows tips and tweaks that involve directly editing the Registry. If you're the adventurous sort (and are conscientious about doing backups), editing the Registry is the ultimate way to customise many Windows settings to your personal preferences.

Benefits: Customise and optimise Windows features.
Cost: Free.
Expertise level: Intermediate-expert.
Time required: Varies.


All versions of Windows automatically create a backup copy of the Registry each time you start your PC, but keeping an additional backup provides extra insurance. Of course, you can't restore changes you haven't backed up, which means you should make backups frequently. Fortunately, there are several ways to back up the Registry.

1. Use System Restore. Windows Me and XP users can create System Restore points, which back up all data (including the Registry) so you can restore your system to that precise state. You should run System Restore manually before you make major hardware or software changes or try to work with the Registry. Click Start-Programs (All Programs, in XP)-Accessories-System Tools-System Restore, choose Create a restore point, click Next, and follow the directions.

2. Use the Registry Editor. The export capability in Windows' Registry Editor can back up parts of the Registry, or create a full backup. In Windows 2000, this is your best option. Click Start-Run, type regedit, and press . Select My Computer in the folder tree, select File-Export, and fill in a file name and destination. For added peace of mind, save the file on a CD-RW disc or other removable media.

3. Copy the Registry files manually. In Windows 95 and 98, the Registry resides in System.dat and User.dat in the \Windows directory. In Windows Me, copy Classes.dat too. To see hidden and system files, you'll need to set Windows Explorer to show them. In Explorer, choose View (95 and 98) or Tools (Me and XP); then select Folder Options, open the View tab, and pick Show All Files (95 and 98) or Show hidden files and folders (Me and XP). Once you can see them, copy the files.

4. Use backup software. Check your backup utility for an option to back up the Registry along with the other files on your hard drive. Some backup utilities do this automatically; others require you to specify Registry backup.

5. Run Windows' Registry Checker. For Win 98 and Me only - see section B, below.


Windows 98 and Me include a background utility called Registry Checker. When you boot your PC, Registry Checker scans for problems; if it can't fix them, it restores the most recent Registry backup.

If you keep your PC running all the time, it's a good practice to reboot the computer daily so Registry Checker can do its work. You can "also run Registry Checker manually (especially before and after making system changes that don't require a restart). To do this, click Start-Programs-Accessories-System Tools-System Information, open the Tools menu, and click Registry Checker.


The longer you use Windows, the more cluttered the Registry can grow, especially if you regularly install and uninstall software. That's because some applications don't remove all traces of themselves when you uninstall them. Orphan Registry entries can cause problems such as sluggish performance or even system lockups, but the more common result is a bloated Registry that takes longer to load. Registry Checker (discussed in section B) doesn't clean out invalid entries.

If you still use Windows 95 as your operating system, you have a built-in Registry cleaning tool. To access it, click Start-Run, type regclean, and press .

In versions after Windows 95, Microsoft didn't include RegClean, so you'll have to use third-party utilities. Two free ones are available: EasyCleaner (, available on this month's cover CD) and RegClean (available at Neither works with Windows XP, but XP's Registry structure doesn't develop as many problems.

For the most comprehensive Registry checking, cleaning, and optimising, however, you'll need to purchase a utility suite such as Norton SystemWorks ($125 for the Standard version and $160 for the Professional, or Ontrack SystemSuite ($159,, Both utility suites have comprehensive features that fully check, optimise, and maintain the Registry, going far beyond Windows' built-in Registry tools or the free add-ons. Both work with all versions of Windows from 98 through XP.


With a bit of surfing on the Web, you can discover numerous Registry tips and tweaks for customising various Windows features by editing the Registry. One of the largest selections is located at the Windows Registry Guide (

If you have a broadband (cable or DSL) Internet "connection, you'll find that tweaking the Windows Registry is almost always necessary for getting maximum data speed. Two helpful sites to check for "Windows Registry information are DSL Reports (; select RWIN in the 'Jump to topic' drop-down list box) and Speed Guide (www.speedguide.netCable_modems/cable_registry."shtml).

The easiest way to make changes to the Registry is with a .reg file; such files are downloadable from some of the sites mentioned above. Double-clicking a .reg file immediately incorporates the changes into your existing Registry. (Make sure you have a backup first.)To input other changes, you'll need to use RegEdit, a feature that's available on all versions of Windows. The example that we illustrate here turns off the AutoRun feature of your CD-ROM drive - if you'd prefer not to have a music CD automatically start to play or have a program CD automatically start up, this Registry tweak will solve your problem. Some versions of Windows permit you to make the same change from the CD-ROM Properties box. In Windows XP, you can perform many (but not all) system tweaks from menus, without having to edit the Registry.

WARNING: Editing the Registry can cause problems - an incorrect entry can "break" your PC. Follow the directions carefully, and make absolutely sure that you have a current Registry backup before you begin.

1. Start RegEdit. Choose Start-Run, type regedit, and press to run the program.

2. Find the key. The key for changing the Windows CD-ROM AutoRun feature is at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cdbcdrom.

To find the key, you can navigate through the hierarchical menus or you can press -F, type cdbcdrom, and press . RegEdit will stop at the desired key. The name of this key may vary - if your Registry doesn't contain cdbcdrom, try searching for cdrom with the Services folder highlighted in the tree listed above.

3. Change the key value. Double-click the AutoRun entry in the right-hand window. In the Edit DWORD Value box that pops up, change the '1' in the 'Value data' box to 0 and click OK.

You will need to exit RegEdit and reboot your PC to bring the change into effect.

Join the PC World newsletter!

Error: Please check your email address.

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Stan Miastkowski

PC World
Show Comments

Cool Tech

Crucial Ballistix Elite 32GB Kit (4 x 8GB) DDR4-3000 UDIMM

Learn more >

Gadgets & Things

Lexar® Professional 1000x microSDHC™/microSDXC™ UHS-II cards

Learn more >

Family Friendly

Lexar® JumpDrive® S57 USB 3.0 flash drive 

Learn more >

Stocking Stuffer

Plox Star Wars Death Star Levitating Bluetooth Speaker

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Latest News Articles


GGG Evaluation Team

Kathy Cassidy


First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni


For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Steph Mundell


The Fujitsu LifeBook UH574 allowed for great mobility without being obnoxiously heavy or clunky. Its twelve hours of battery life did not disappoint.

Andrew Mitsi


The screen was particularly good. It is bright and visible from most angles, however heat is an issue, particularly around the Windows button on the front, and on the back where the battery housing is located.

Simon Harriott


My first impression after unboxing the Q702 is that it is a nice looking unit. Styling is somewhat minimalist but very effective. The tablet part, once detached, has a nice weight, and no buttons or switches are located in awkward or intrusive positions.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?