This indicates a problem with your computer's hardware, specifically with the memory (RAM). You should have a computer technician examine your computer for hardware problems. Imagine it as the "Check Engine" light in your car coming on.

You can use Memtest86+, available from the Memtest86+ website, to test your computer's memory. This unfortunately isn't as simple as installing and running a program, because the program has to be run before Windows loads in order to access your memory. The way this happens is that the program is placed on a CD, floppy disk, or USB flash drive, and your computer is started from that device rather than the harddrive containing Windows. The program will run a number of tests, and when it completes a full "pass" (which takes about 30 minutes on most computers) it will start over from the beginning. Errors are logged as red lines of text, of these appear there is definitely a problem with your computer's memory that will need to be corrected, most likely by replacing the failed memory.

I suffered the above situation several times on a new netbook (runs on Windows 7 starter, fully updated). Had the memory checked by both the native memtestprogram of Windows 7 starter and memtest+ v4.02 (complete check, extended tests included): no memory errors were detected. The problem only occurred when using Firefox version prior to the current so far (I have 3.6.11 updated on oct. 23, 2010). 1. Is FF capable of generating such memory-problems? 2. if answer 1 = yes: did the last upgrade fix the problem?

addendum: the problem mentioned above is not solved by the latest update, and the problem not only occurs when using the scrollbar but on various occasions and exclusively when using Firefox. With the use of other applications (including Windows Internet explorer) the memoryproblem does not occur (upto now that is)