Help...phone keeps saying memory card removed and shuts off about 2x an hour!!!

Recently, as of last Friday, my 8830 began telling me that a memory card has been removed, but I don't even have a memory card. When this happens, the phone resets the service. This only happened Friday night, that I know of, but today it has begun doing this about twice an hour, and has even shut off the phone a couple of times. To get it to turn back on I had to take the battery out and restart it. I'm worried that my phone might be really screwed up, and I'm not a huge fan of it turning off as I need it for work. I don't know what's going on, but I'd really like this to stop. If anyone has any info on this for me, it would be greatly appreciated!!!

UPDATE: I finally noticed what the phone was saying. After it would tell me that a media card had been removed, it would say "device error:348" and would force a reset. I don't know what to do about this, to my knowledge I did not get it wet, I didn't do any updates, and haven't damaged the phone in any way. It just sort of happened Friday night. I would really appreciate it if someone could help me out here. I'm somewhat Blackberry illiterate, but I really need this phone for work, so any help would be great.