Mouse Bug

[plutomaniac]

Can you try:

1. A steam file integrity check?
2. Deleting cfg files at Documents (check guide, reset settings)
3. Reinstall the latest graphics card drivers in case there is some sort of visual corruption
4. Close ALL background programs and 3rd party services in case there is some sort of interefence

Do you know if you are having the same issue at Amnesia The Dark Descent? Also if you have a gaming mouse with custom settings and utility, try turning that off.