Posted 06 December 2012 - 22:49
This might sound stupid, but, what does your mousemat look like?
A lady here had the same issue with different mice, until I figured out it was fine when I took away her mousemat. It had a pattern on it including areas of red that were quite close to the colour of the optical light. I figured the mouse was getting "lost" over those areas as she moved it and it couldn't track properly. She got a new one, of a light solid colour, and it's been fine since.