I am running the last version for windows, which is 0.6.1 (from http://www.joachim-breitner.de/archive/arbtt/ ).
When a window with elevated rights is open on the desktop, arbtt-capture will crash. It does so with this message:
arbtt-capture.exe OpenProcess: permission denied (Zugriff verweigert).
This can easily be reproduced like this:
Open services.msc (the windows tool that lets you view, start and stop your services). Opening it will prompt you to give it Administrator privileges. You will do so.
Start arbtt-capture.exe (or if it is running, wait for ~1 minute until it tries to capture another sample).
It will fail with the mentioned message 100% of the time.