Without notice, it just shuts itself off several times a day, then very slowly re-boots to normal operation. This used to happen when I first got it about 18 months ago, then the problem stopped for over a year. Now it's back.

Anyone have a similar experience or a fix? Thanks

Have you tried a new battery or checked the battery contacts? the contacts could be dirty. also did you drop or get the phone wet?

Reload the OS? Try updating to the latest offering for your model, which I believe is OS 5: Latest OS: 8330 5.0.0.724/5.0.0.438 (Multilanguage)