I've had trouble with Vista and other games affecting the HL mouse. For example playing WC3 increases your mouse sensitivity on NS for some reason and after that even changing map seems to boost the effect. Getting a fresh restart for the PC removes the problem until you play some of the problematic games again.
Seconding this!!!
After my initial few games after taking acceleration off I found my aim improved hugely. Then the last week I decided it really wasn't all that different.... Until my computer crashed and I restarted my pc... Only to find that I needed to triple the in-game mouse sensitivity....
The fucking thing had reverted back to mouse acceleration!!!! Are you on Vista 32 bit? I don't even play other games so for me at least there's some other program that's constantly reverting me back to mouse acceleration. Razer Krait drivers don't get any newer than 2006 apparently :<
Thy shall smack daun your enemies with the power of the spit and the holy chukle! --------------------------------------- http://www.youtube.com/watch?v=ASaZmqYa-2Q