I have a problem with my wp7 phone. It crashes very often with a white screen.
It happens randomly, with or without sim card. Sometimes, when it crashes there is a long sound from the speaker (kind of like error) and then it vibrates 5 times and crashes again. I did a reset (settings/about/reset) on it and it crashed two times.
BTW What I though is settings/about/reset will do a hard reset and restore the software to factory default, but I see that the OS version is 7.10 (was 7.0 when I bought it). But it looks a bit strange. Firstly it doesn't have letters in the app list
Looks like some 7.5 features are there and aren't.
My phone is a dev phone and I think it started when I didn't extend my dev account. I'll try to unregister the phone with Developer Phone Registration.