Hi,
As you mentioned earlier, seems like that virus is not letting smc.exe service to start, virus always keep an eye on installing software and know how to kill those, you have 2 options here,
1) follow all the steps i mentioned earlier
2) try replacing the image file execution key ( on your own risk, i hope u know how to back ur registy , if not please use google)
take a back up of entire registry
then take back up of this key Image File Execution Options
from
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
now take a back up of Image File Execution Options
entire value from any machine which is running fine with SEP , (not infected with virus)
put this key to our infected machine.
Try installing the software. I'm sure that this should work
PS: I bear no reponsible to editing registry
more info about this key can be found at and the reason whats keeping an eye
http://blogs.msdn.com/junfeng/archive/2004/04/28/121871.aspx