Hi Nimal, why don't you go to Tools, Internet Options then the Advanced tab on each computer and compare what's ticked and what's not setting up the computer that can't open the web page to the same settings as the one that can. PP.

Here's a couple of possibilities: online banking sites normally require your browser to accept a cookie and also may require a popup to run (to enable a login). There are a couple of areas you need to look at - first the browser (I don't know what you use - though Internet Explorer is the common one) may need to be adjusted to have your netbank site as an allowed site in the security section (your help will guide you through this)and you may need to allow cookies from this site.
The other often overlooked thing is your browser may have a Google or Yahoo or whatever variant toolbar installed on the offending computer and some of these have their own built in blockers/filters which need to be adjusted to allow online banking sites to run cookies or a popup.
My advice is to uninstall any of these "add on" toolbars however I know that most software you use/load has an option which tries to install these things - they are just more overheads for the computer to run although for some they may be a convenience. I use the Google "Chrome" browser as much as possible with Mozilla Firefox 3 there as another option as some sites (eg. edu.au) won't run their webmail on "chrome" (yet).
Hope this helps as to get more specific I need more specifics to work from.
Priebs

Good advice for the others.
One thing they have missed - if you have an AV or IS (Anti virus or Internet security program) running such as Nortons, McAfee, or the likes, it may be also stopped from there.
Check your security settings - cookies etc with in the resident protection program as well.
Make sure you are typing in the web address from start to finish yourself, there is/was a number of viruses floating around at one stage which would, hijack you browser send you to a false banking pages and when you entered your login details would capture that data.
Hope this helps,
Micky.
www.mbinfotech.com.au