Alright, I'm not sure how long this has been going on, but recently, I began to notice a constant blinking of my hard drive activity light and my mouse cursor switching between the normal and "loading" cursor at the same rate, which is about twice a second. I've tried out a few things to find out what it could be, but no luck.
Dell XPS M1710
2.0GHz Centrino Duo dual-core processor
NVIDIA GeForce Go 7900GTX
100GB Hitachi HTS721010G9SA00 ATA drive
Windows Vista Ultimate 32bit
The LED/cursor flicker doesn't happen in Safe Mode, but it does occur in a regular boot with all startups and non-Microsoft services turned off. I went through the Process Monitor and didn't find anything malicious running either.
As for any ideas of what may have happened: I didn't notice it until after I had a Dell technician come out and replace my video card (my old one was failing), which may or may not indicate that's when it began happening, but I have no idea.