Very great, many thanks for this. I even succeeded to run xperf under WinXP (this is something I wanted to share with the community to give something back): - first I extracted "xperf.exe" and "xperfctl.dll" from the "wpt_x86.msi" (you can use 7zip to do this) - i copied this to a temporary folder - i started a dos box and changed to that folder - i ran the xperf logging like described and stopped it like described I did NOT succeed viewing/debugging the etl-file in WinXP, but: I just copied the "*.etl" to a Win7 computer (where I have a normal wpt-Installation running) and doubleclicked the *.etl-file to find results... It seems to work and I could identify a troublemaker on the WinXP machine (see attachmed file, etl was created with xperf in WinXP and diagnose ran in xperfview@Win7, thats why there's the aero window style). So thank you for this thread and I hope someone could benefit from my WinXP-trials with this tool...