>I have a big problem and need some fast help. After deploying a .NET application on a server, one of the core windows 2000 server dlls is messed up (msvcrt.dll). I noticed the size is about 20K less than the one on my machine. I have tried to copy over the dll but keep getting the message that the file is in use and cannot be overwritten or renamed.

A system DLL that isn't the right size, date, or in the expected location is possibly a sign of a worm.

You should scan the system immediately with an up-to-date scanner, and probably use two to be on the safe side. Don't rely on automatic updates and scanning. Run both the virus definition update and scan manually.

Updated: MS advised a client to run a system scan from http://housecall.trendmicro.com/ which found a worm that their Symantec Corp. edition hadn't found. I haven't used this service so I can't vouch for it personally.