Check to see if GPU acceleration is turned on. If not, make sure that Windows didn't use some sort of arbitrary driver for the video card, instead of an up to date driver from the card maker's site.
[EDIT] I meant to add that Windows did exactly this to me a few years ago, when updating from Windows 7 to Windows 8. You'd think it unbelievable, but that's what the buggers did. Trashed my real deal NVIDIA driver, and replaced it with a generic Microsoft version.
Not so sure of why your mouse wheel is not affecting the brush size anymore.... but I have do have two ideas that are really work-arounds.... but I prefer using both to your method, and hopefully you will too!
1. You can easily INCREASE or DECREASE the size of the brush by clicking the LEFT or RIGHT Bracket keys to Quickly increase or decrease your brush size
2. You can Press and HOLD the CONTROL key and the OPTION key (Mac) and click an hold the mouse down as you SCRUBBY
drag your mouse to the right or left to change the diameter of the brush. The brush on your screen will turn red to view the size. You can also scrub up or down to change the brush hardness.
hope that helps!~
Ummm how do i do that? I need steps plz
uhh thanks but no, i only like the mousewheel is so comfortable