If I have both a browser window and a mail/news window, if I try to minimize the browser window, it immediately un-minimizes itself. Earlier it seemed to be doing it all the time. Now it only does it if the mail/news window is minimized. This did not occur with Mozilla 0.9 or 0.8.
Are you using a build from before 3-28-02? If you don't know just tell us the "Build ID" that's at the end of the title at the top of the window. If so this probably a duplicate of bug 120155.
I have seen the same behavior (unminimizing when minimized), but I never use the mail/news window at all. I have not been able to consistently reproduce, nor have I seen a definite pattern in when it happens. Here's what I know: I use tabs and separate windows extensively. Even so, I have seen this problem happen when there is only a single window open, and that single window contains no tabs. If the window is minimized from being maximized it comes back in the un-maximized size, (i.e. the last un-maximized window size and location). It does not matter if the window is maximized or un-maximized. When minimizing, it restores to the un-maximized size. I have seen this bug in 0.98, and .99. I am pretty sure I saw it in 1.0 rc1 yesterday, but I am not positive I had upgraded that box. :( My current build number is 2002031104 (0.99) ..From what I've read, this -could- be a dupe of bug 120155, as previously suggested.
The bug is in 0.9.9 and RC1 This bug is invalid if you are using another build (too old) *** This bug has been marked as a duplicate of 120155 ***