Troj/ZlobDrop-C is a dropper Trojan.
Troj/ZlobDrop-C will drop and run msmsgs.exe in the Windows system folder, currently detected as Troj/Zlob-H.
Troj/ZlobDrop-C will set the following registry entry:
HKLM\Software\Microsoft\Windows\CurrentVersion\Run
MSN Messenger
"msmsgs.exe"