It's probably still in the Run section of your registry. Start regedit and look in:
\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce and \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEx
There's probably an entry for asmonitor.exe in there, which you can remove.
If that's not it, then there's probably another program running that is adding asmonitor.exe back in again.
NOTE: The usual warnings about changing your registry directly apply - the registry is at the core of Windows and inadvertently changing the wrong thing can leave your application or Windows setup unusable