Its possibly a bad batch.
I had some friends get new computers all at once from the same supplier and they all got Microsoft mice for them.
However, they had an interesting flaw in them where the mouse would randomly report exponential speed increases.
For a test, I set up a image with a square box 1/3rd of the width of the screen, and spent 10 minutes just drawing circles inside that box, and found it impossible to stay inside the box.
As usual, Microsoft Knowledge Base articles on the subject were useless, they suggested simply upgrading the drivers, which were already up to date, or using "mouse smoothing". Neither of these solutions worked of course, because the mouse was sending errors that were 3 times larger than any reasonable movement that could be expected from a user.( ie: how are you going to smooth out noise that is greater than signal ? )
Also, as this symptom occurred on non-windows platforms as well as windows platforms, I found the windows-only solutions unacceptable in principal, and requested replacements from the suppliers. ( They replaced them with equivalent Logitechs, which JustWorked as expected ).
Notedly, these weren't exactly high end mice so manufacturing defects are more expected of them, but the concept still holds. IMHO, your mouse has a manufacturing default, and should be subject to warranty replacement.