Gigabyte P55 motherboard? Windows 7? Radeon HD5xxx Card?
If you have the above, you might have noticed that your cursor will randomly blow up to about 4 times the size! I only noticed it today, but it's probably been happening all week, and I hadn't noticed.
Anyway, after some research, it turns out it's an issue with the Gigabyte P55 BIOS's. I've just updated mine, and it seems to have solved the problem. Quite why a motherboards BIOS would affect the size of the cursor is a bit baffling, but it appears to be with power saving features of the card/CPU of something. Didn't really follow it all! There's also apparrently an issue watching flash movies at full screen as well which this can help with. This is thread I got the details from: -
http://forums.amd.com/game/messagevi...VIEWTMP=Linear
I know you lot could probably have solved this yourselves, but thought I would post here just in case people were looking for a solution.