To day by mistake i clicked yes on pop up ads; immediately norton antivius identified it to be as a virus, but it said unable to repair. Now whenever i restart my computer, i keep getting the following error message asking me whether to continue, ignor or cancel and i have been cancelling it fearing i may damage my system. I hope it is not serious proble. The error message in small box is as follow: 16 bit m-dos system C:windows\system32\scchk32.exe The NTVDM has encountered an illegal instruction cs: 055f IP: 0122 OP:f095 b1 choose'close' to terminate the application Does anyone know what it means and how do i fix it?. I tried virus scan now and norton AV is telling me no virus found. But i keep getting the error message. I also checked with antispyware and none found. please help! Thanks and I appreciate.