Help explorer eating resources

Hello all I am having a problem explorer.exe is using 50%resources all the
time I used process explorer and this is the culprit
ntdll.dll!RtIntegerToUnicodeString+0x67 anyone have any idea what it is? It
also effects the start menu the start menu locks up constantly and the only
work arround is keeping taskbar set to classic. Other problem is if I right
click on desktop and go to "new" explorer.exe freezes and needs to restart.
I scanned with numerous anti spyware and antivirus programs and nothing.
Please help this is driving me crazy.