well, about 1 month ago i had a virus that my computer guy said moved around files and stuff. he said that he had fixed it. anyway i wanted to go and play some COD 4 and i realised that it was really laggy, so i turned down all the graphics options and itwas still laggy. so i ran an 'dxdiag' and found that my graphics had gone from 3700mb down to 1696mb.
Does anyone know how to fix it?