Perfmon stops logging after 1-3 days even duration set to 3 weeks at windows 8.

On the Quality Assurance apartment that I work, we use Perfmon to keep track of memory leaks by logging private bites and handle count for the applications we test.

But when we use windows 8 we always have the same problem.
Perfmon stops logging after 1-3 days. Even if we do no settings at the Stop Conditions or we set Overall duration to 3 weeks.

Please help, we need to perform stability test at our application on various operative systems.