HP Prime problem. Calculator resetting itself

[Michael K-K]

Prime:
SW-Version: 10077
Hardware Version: A

Computer OS: OSX 10.5.11
VMWare Fusion, Windows 7

Since the update to Version 10077 my Prime is nearly unusable.
First the Update went not smooth: When reaching 100% the process stopped and I had to reset the Prime with a paperclip. While the instruction said the memory of the Prime would be wiped completely it retained all my programs - so I wondered whether the process went correctly or not (the info shows the updated version of the OS).
From this point on I experienced random crashes, restarts and hanging at the start-screen (paperclip). Today the Prime crashed severely loosing all its memory and restarted 3 times in a row, loosing also the settings.

I'm really sad - I can't use this calculator anymore because of this instability.
Is there something I can try to fix this?
I already tried the above mentioned methods (F C O, Format Disk).

With the previous version everything went fine, the calculator was very stable. Maybe downgrading?

Michael