Microsoft Security Essentials
Upon install a file was found by MS SE. It didn’t say it was a virus, malware, etc. - just unknown and asked me to send the file to MS for further diagnosis. I did.
Maybe contact MS to resolve any issues. Don’t want them giving your game a bad name on all Windows platforms.
Which file? It may have been corrupted during download. Try verifying the game cache through Steam if you encounter issues.
I use Microsoft Security Essentials and have not encountered that yet.
I’ve had this same problem, in addition I cannot find any servers listed.
The file that MSSE is catching is UDK.EXE