[tunnsie]

These watches are cool but beware they all come from one Chinese factory and are resold in a variety of sites.
Also it is common practice to put fake firmwares on them that spoof larger flash sizes than really exists. So if it says 2 gig but is only 512, you will eat into memory addresses that will pooch the OS. This would explain your symptoms. Try and see if only one MP3 applied will cause any issues.
If not then it's something else. I have and know of two other people that have purchased these things and we all have returned them. Actually mine was from a Japanese company that would not return tech e-mails so I recovered my costs from my credit card company on it.

They are a nice idea but not ready for prime time.