In KDE I'm sometimes losing the Firefox scroll bar. The space where the slide bar goes is there, but no slider. I can still scroll if I point the mouse where the slider should be. It's as if the slider has taken on the background colour.

There are also some problems with tick boxes vanishing at the same time. I've tried changing the window themes and colours but nothing helps. Even rebooting doesn't fix it and the fault seems to occur randomly. Konqueror doesn't seem to suffer the same problem as far as I can tell.

Ideas would be very welcome.