Yeah that sounds like you are having tracking problems on your mouse, before when you used acceleration I imagine you didn’t have to move the mouse as fast as you do now with the mousefix. Hmmm go into mspaint and try it, set it on a low dpi and record your movements back an forth in the same pattern to see if you are doing straight lines, if it is *edited*ing up then it is probly the mouse you are using.
Specifically what mouse are you using, a g5 or any other lazor mouse for that matter can have tracking problems that cause what you are specifically describing when moving the mouse really fast. In fact when I used to use the g5 I experienced exactly what you are describing after I became a low sensitivity user. hmmmm, try the two files I attached, one is to measure the polling rate of your mouse, the higher the better, 1000 is the most you can get with a usb port, if you are getting lower than that and using a laser mouse then you are having tracking problems, other than the new blue logitech g5 i don’t know of any lasor mouses that get 1000 polling rate, the other program over clocks your usb port to possibly a 1000 hz there if your mouse can handle it. If all else fails then l I also attached the mousefix zip folder again so you can undo it if you don’t like it. It takes some getting used to, it ain’t meant to be something that immediately improves your game, but rather make it your accuracy more consistent as you get used to it. It is *edited* hard to find a pro out there that doesn’t use it. Not saying it will make you as good as them, just that they use it for a reason, because mouse acceleration can *edited* your game up. If you want to uninstall it you can with the cplmousefix.rar i attached below.
Also it may be as freeman said, you might be having problems with whatever you use as your mousepad. Granted I think it might have something to do with what I said above as you mentioned it starting after you installed the mousefix. Hope this helps.