Since it can't find the DLL, its probably already been removed. The problem is, the Registry entry that's trying to run it is still there.
Click Start, Run and enter REGEDIT Go to:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
You should see an entry in the right pane, similar to {12EE7A5E-0674-42f9-A76B-000000004D00}. It will use the RUNDLL32.EXE to invoke the STLB2.DLL file. Right click this value and select Delete.