Hello, I just want to place here that I had the exactly same problem than "BlackAle", y all the ones that "ken winston caine" had    Thanks to JaRC for the super important code he placed here:   
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib
and in all likelyhood you wil find an item named "Disable Performance Counters" in the right hand pane, set it to 0 and everything should be right as rain the next time you boot.
Thanks to this info. PT is working properly now, and making my PC run faster than ever.
Very Good job Mouser ! 
God bless all of you, bye 

Thanks to JaRC for the super important code he placed here:   
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib
and in all likelyhood you wil find an item named "Disable Performance Counters" in the right hand pane, set it to 0 and everything should be right as rain the next time you boot.

This message from several years ago proved invaluable to me just now.  I had tried Process Tamer briefly in the past, but yesterday I decided to use it again.  To my dismay, I couldn't get it to run.  Same story as so many other messages in this thread, but I wasn't using any of the programs mentioned.  However, when I came upon JesusInsideMe's message, I went into RegEdit and gave it a try.  Bingo!  All is now well. 

I now realize why PT had worked when I tried it earlier but hadn't this time until I made the registry change.  A week or so ago I tried JV16PowerTools' settings to speed up my computer.  Sure enough, one of them had to do with disabling performance counters.  None of what I did made much difference in my computer's speed, and I simply forgot about it.  But I'm almost certain that that was what blocked PT from running.

Anyway, many thanks to JarC and JesusInsideMe (who called my attention to JarC's message).

now the right thing for me to do is check this registry setting and warn the user if its disabled.

Good idea, but you already get good points for including a link to this thread in the Help file!  That's how I found it.