ntoskrnl.exe changed

ntoskrnl.exe changed shell32 dll user32 dll kernel32.dll avg says changed.....this is what a avg scan comes up with.....i had a trojan yesterday...seemed to set rid of all bad stuff adware and trojan ....scan after scan comes up clean except for this avg ..result.........what made me know something was wrong is when i tried to play avi it started normally but after a few seconds sound was all messed up and puter jamming up a bit...all seems to work ok till i try and play a movie or song......im running x/p sp2 pent 4 2.53 1 gig memory...sry for my not explaining this better as i am self taught on puter and obviously have limited knowledge....please help the trojan or whatever i had made it so i couldnt do a system restore....