thanks a lot for ur suggestion even i felt that symantec makes computer system very slow, on this note could u please reffer me a good antivirus which would be effective another anti virus i use is Macfee.

well i was trying to install symantec in safe mode thats because my computer is full of virus and i was not able to install symantec in normal mode so i tried in safe mode.

to be very precise my computer is infected with a virus that closes almost all dialog boxes after few seconds it was opened, any dialog boxes like system properties, or the one which opens after we double click on setup file to install due to that i m not able to install any program and if i m not wrong name of the virus is 'smss.exe' so pls help me out with this issue....