Themisive, Check out the links/threads at the links below.
I have been getting files named Perflib_Perfdata_5b8 (the last 3 characters seem to vary) in C:\Windows\Temp for a while now. However, recently these types of files have also begun to appear in C:\My Documents\myname\Local Settings\Temp, the files are: Perflib_Perfdata_1b4 (and again the last three characters seem to change).
Thus in each of the two files, I could - and sometimes do - have as many as 6 or even more of these files. That they are associated with a programme is evident, but I don't know which programme is generating them.
Obviously I would like to stop them, or at least cut them down, I have checke the Event Viewer but can't seem to find anything so I wonder, has anyone else ever come across this problem.