Desktop Shortcuts don't work

[AllanKu]

Windows XP Firefox 2.0.0.8

If Firefox is running, a desktop shortcut will not open a web page in the browser.
Desktop shortcuts only work if Firefox is NOT running. Then if I double click a desktop shortcut Firefox starts and opens the page

Shortcuts on the browser bookmarks toolbar do work.

I'm sure the desktop shortcuts used to work. File association seems to be OK

Any ideas?

[FirefoxWiz]

Let's see, do you have any extensions that relate to only being able to have one browser window open?

[AllanKu]

I don't have any extensions as far as I can tell

[AllanKu]

Sorry, I was looking at the wrong thing.
Have XPLink Scanner
Talk back
PDF downloader
No Script
CAlling ID Link Scanner

Don't know if any of these relate to having only one browser window open.
I can have more than one window open if I hold down Ctrl while clicking on link