About two weeks ago(I've had my n900 since dec), my n900 started losing connectivity; this happens about twice a day. No cellular network is found at all or the signal will show as full, but I get a "general error" when trying to dial. Connecting to GPRS/3G fails, connecting to wifi fails. If i turn off the radio/turn it back on, nothing changes. The only thing that works is power cycle. I have tried reflashing a few times, and run without ANY 3rd party software/testing/devel. I have T-Mobile in the San Jose,CA area so I don't think that poor signal could be the culprit. After a reboot I'm back at 3.5G with a steady signal for about 9 hours...

did you find what is causing this problem?
recently i am getting the same problem, i thought wifi switcher was the culprit but now i'm not so sure because it happens even when it's not toggled.

did you flashed the eMMC? if you didn't then i suggest you do it and reflash again. No one else have any problem with their N900 like you. So if flashed both emmc and OS still not fixed your problem then it could be that you have got a budget device, take it back for warranty