(NOTE: pictures arent here because i dont have a high enough group, you can see them at my screenshots on steam (my steam name if hoofy_potter)
Ever since 1.5, or the 1.5 beta, I've been having a weird lighting glitch, (no it isn't that not a glitch glitch) when i go under an arch or other structure above me, shadows surround my position and scratches appear, when i get out from under, the lands fully bright, its very ugly, skyrim's community is getting more skilled with modding and i try to play the game, but its to ugly, i even deleted all files except my saves and mods, here's some pictures of the glitch:

as you can see, I couldn't capture the scratches, but you can see how there's random shadows in mid day, here it is not under something:
note that this is the same time of day,

you can see a scratches here:


here's my pc specs:
OS: Windows seven
Processor: AMD Turion™ II P540 Dual-Core Processor.
RAM: 4.00 GB (3.74 GB usable)
System type: 64-bit OS
Graphics card: ATI Mobility Radeon HD 4200 Series

Thanks for the help