How to remove a system file?

can any1 provide to resolve "CTDRVMKC.EXE" operation. i m trying to fix it using netsh command. physically i can't see this file, but my anti-virus confirms me its' a Trojan Program. i can see a path using netsh firewall and it is "c:\windows\system32\CTDRVMKC.EXE". but can't see anything there. In Windows firewall, it is treated as an exception named "LAN Router". I have an anti-virus and it can't fix this problem. and I can't using yahoo messenger for this thing.
Plz, any1 can help me to resolve this issues without re-loading OS?
Thanks
Joy

I can't seam to find an AV that knows this, try removing the file with Ghipo's MoveOnBoot. Here: www.gibinsoft.net/gipoutils/fileutil/index.htm

This will mark the file for deletion on next boot, so when you restart, it will be removed before it even has a chance to execute.

You could also upload the file to www.virustotal.com/ This site will scan the file using more than 40 well known anti-viruses and will tell you which and what virus has been detected.