The error behind this message is: System.InvalidOperationException: Process performance counter is disabled, so the requested operation cannot be performed.

Probably has a third party application deleted an important system file called perfc009.dat. Just download it from here and extract with WinZip it to your system32 directory (normally "C:\WINDOWS\system32\"), then start VisualCron again.

Also, check that you have read access to the following key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT \CurrentVersion\Perflib\009