Black screen after windows XP logo (help!)

Everything was fine with this PC for the last week until 2 days ago. come home from work and I get a black screen of death.

a few details. it's a PC with only a motherboard (no fancy video card or sound card - does have a wifi card though) it's an official XP service pack 3. I use a CTX flatscreen with it.

My C drive is down to a bit of a risky 2GB's but it should be ok with that. It hasn't moaned to me about limits yet.
Did a scan with a fully up to date anti malware bytes thingie and it found nothing so I don't think it's some nasty virus. Please help me! Safe mode is horrible you can't do anything - I'm surprised it let me on the internet though.