what mousepad do u use?
i had the same probs with a mousepad that had pictures and a surcace that not smooth....
try a clean "fast/smooth" surface mousepad, e.g. Speedpad

this problem occures when the mousepad is not ready for optical ... in most cases its reflecting the backgroudn to much .... the struckture of the mousepad will be false detected as motion ...
this is not the picture on the mousepad itselfe ... its the furface .. the furce must hafe a fine struckture for an optical mouse to work perfect ... a mirror like surface is no good here ... just get a new mousepad ready for optical mouses and voila ..

that´s what i meant
thanx for translation, Mertsch ! (spam)

use non-reflective object as your mouse pad. I use a book with smooth and non-reflective surface and it works flowlessly.

i have a mousemat but a friend of mine told me they were unecessary for optical mice so im using it on my wooden computer desk

I use an optical mousepad from EverGlide which works quite well but I can't recommend them as the feet fall off so get something along the same line as EverGlide & your mouse will work much better.

its part cheap mouse part the wooden surface.
try with a regular blue mousepad before getting a new mouse
my logitech mx500 works fine on my table, but i use a mousepad anyways, so i wont wear it down as fast and its more comfortable aswell.