Gilthoniel, If you by chance installed the YAHOO Toolbar uninstall it and see if the problem is corrected. The YAHOO Toolbar is known to cause the problem you're having for some people.
I am running IE 6.0 on a Windows XP Pro machine with SP2 loaded, and in the last month or two I've begun to experience an extremely annoying issue. I can only have one browser session of IE at a time. No matter what I do, when I try to open a second session, the new session replaces the old one. It doesn't matter if I go to the program icon to open a second session, or right-click on a link in a browser page and select ''open in a new window'', still the existing session is replaced with the new target. The ''back'' option is lost and I have to start over again.
I've tried un-installing and reinstalling IE. I've tried uninstalling and reinstalling SP2, but to no avail. I don't know how to ''repair'' XP itself, as this machine came with XP on it and I don't have the installation disks.
All advice gratefully accepted. I've been using Netscape in the meantime out of self-defense!