When attempting to start monitoring on a server you might receive the below error message:
Error: Input string was not in a correct format
The above error occurs since the counters are corrupt and not displaying their correct names instead just displays random numbers. A sample screen shot is attached below.
To overcome this issue you will need to run below command on the server that displays invalid information for counter names:
lodctr.exe /r %windir%\system32\PerfStringBackup.ini
For more information please visit Microsoft website: http://support.microsoft.com/kb/300956