Yes this is a fairly well known "limitation" of firefox. I put limitation in quotes, because of course, other people think this is the correct thing to do, and that IE and all the others have it wrong.
The solution for FF is to use profiles. Just google for 'Firefox multiple sessions' and you'll see a plethora of pages.
Joined: Mar 08, 2007
Thanks Mike. Thanks a lot for the useful Info.
subject: Firefox overwrites other session's (window's) Cookie.