For those who are using Firefox, and having trouble wherein new (additional) windows will not open, here was my fix:

The followings steps instantly fixed my problem. (This worked for me using Firefox 3.6.8 on a Win XP Pro system.)

1. Start Firefox.

2. Click Tools, then Add-ons

3. If you have more than one Java Console active, uninstall all but the latest one (highest version number).

(It is possible that “disable” would also work, but I chose to uninstall.)

Unrelated diatribe:

I am currently using two laptops. I am slowly leaving a Windows (XP Pro) laptop while transitioning to a Mac (OS X) laptop. I decided (upon principle) to not buy or upgrade to another Windows OS, and as this one slowly dies (first the ability to search my own hard drive went, and lately M$ Outlook won’t let me reply or compose new emails) I am moving to the Mac. However, the foregoing could be applicable no matter what OS you use.