The performance counter "Performance System\Average Disk Queue Length" (PhysicalDisk(*)\Avg. Disk Queue Length) could not be monitored. Please make sure that the performance counter exists. If you are running a non-english version then you might have to adapt the name of the performance counter so it matches the language of the Operating System.
When you get this message for a performance counter you know should exist (e.g. built-in performance counters of Windows like CPU, memory, disks), first make sure that the performance object and/or counter are available for selection in the "Reliability and Performance Monitor" application which ships with Windows 2008 and later.
If the counter does not show up, then it may be disabled in the registry. For the aforementioned counter, navigate to the following registry key:
to 0. The additional link includes more detailed information on enabling and rebuilding performance counters.