lawl mouse sense wtf

When I open VLC or TeamSpeak, my mouse sensitivity lowers dramatically when the program is in focus, but goes back to normal when the mouse is focused on something else. How do I stop this from happening?
I'm using an mx510 with the latest mouseware drivers.

got old computer with usb 1.1 or earlier? It sounds a lot like you've got devices competing for bandwidth. Try seeing if there's another set of USB ports on your PC (usually there's a couple on you motherboard as well as any hubs you've got connected up) and connect it to those