I'd like to add that I am in the same boat. If i remember rightly (this isn't gospel, have been busy) it started on Saturday, AFTER 6 OTA third party software updates. I wish I could tell you what the programs were but I can't.

I checked my application manager log, which told me nothing. Anytime I've had an issue with my phone I've uninstalled apps that I don't use or have been recently installed. I have just done that. Tried to check the log for a list of uninstalled programs but once again, it seems to have cleared itself.

I will update on whether or not the issue persists, I feel it most likely will.

And on a small side note, the holder for the sim card seems loose, particularly when open. It can slide about a bit. Could a few people check that this is common on N900s, if it isn't then that is most likely the issue.

adam, could I asked if you've recently installed new or updated apps, and what ones, if so?