I'm using Mozilla 1.7.12 on Mandriva2006 Free, i586, KDE 3.4.2. The install was from the mozilla website and a DVD bundled with Linux Magazine.

Seemingly arbitrarily the text boxes on websites in mozilla stop working. If i click in them, i get no cursor. If i try to type anyway, the search-while-you-type thingy happens. The closest i can find to what might cause it is when java scripts lauch requested pop-up windows for me to enter a username and password into. After doing that and closing the box, i might lose text box functionality, but the majority of the time i don't.

Also, more recently, the close titlebar buttons stops working, but only in mozilla. I though this might be down to KDE not mozilla, but i nothing else seems to have the same problem. This seems to happen completely at random; i can't get see any pattern behind them.
The only way to fix it is to press ctrl-q, but this doesn't neccesarily close the window in focus.

Any ideas on what might be doing this?

I don't know if it's even available yet, but are you by any chance using the new KDE/Qt interface for Mozilla that's supposed to exist?

I ask because this is the sort of bug I might expect to see with a very new port of well-tested software to another widget library.

Otherwise, I've known software to behave very strangely when a subtly incompatible version of GTK+ is installed, but that is a problem I've witnessed mainly with the Windows port of GTK+. The sort of thing you're describing do sound like similar symptoms, though.

No, i'm using whichever toolkit was with KDE 3.4.2. That's what's got me, though, this didn't follow any updates of anything, it was almost like i wore something out.
I'll see if i can work out which version of GTK moz wants, and check if it's the same as what i have.