Troj/Delf-AC is a backdoor Trojan which allows a remote intruder to gain access and control over the computer.
When first run Troj/Delf-AC drops the files Eexplore.dll and Explorer.dll to the Windows System folder, copies itself to the System folder as Rvchost.exe and creates the registry entry:
HKLM\Software\Microsoft\Windows\CurrentVersion\Run\
RVCHOST.EXE = %SYSTEM%\Rvchost.exe
so that Rvchost.exe is run automatically each time the computer is restarted.
Troj/Delf-AC may delete the files Mstask.exe and svchost.exe from the System folder.