Strange Change in Mouse Sensitivity

I wasn't sure where to post this, but please move it if its in the wrong place .
I was playing a mod for counter-strike (a variation of the popular zombie mod) last night, and in the middle, my mouse sensitivity suddenly got really slow. I had been switching in and out of the game and when playing the zombie, the sensitivity is messed up due to the change in field of view, but even after closing the game, restarting the computer, and restarting Logitech's setpoint (I use an MX518 if that means anything), it was still really slow. As far as I can tell none of the settings were changed (the game sens., windows sens, and setpoint sens.). So, basically, I'm wondering what could have happened and if there are potential fixes. I searched the internet and forums for a while, and I couldn't find anything. So thanks for your help!

It could be driver problems, but everything is updated.
And I don't understand how overheating would cause that problem ... Its all very strange. Perhaps an unwanted change in the registry that for some reason didn't show up? I dunno... I've never encountered anything like this. Thanks for the quick reply.

I'm less concerned about corrupted hardware than I am about changes that were made without me knowing or being able see. Do you know of anything like this that has happened before ?

drivers may not be compatible

I have the exact same problem mx518 too, only difference it happened when I was on a website but i was in-game

I had this issue between CS:S, VLC player and various other programs. I have G7 and use setpoint 4.60.122. I solved the problem by opening Setpoint, going to the 'chess piece' or mouse game settings tab and unchecking the game detection box. I then selected setpoint implementation for speed and acceleration. No more sensitivity changes.