WordPress MU

Ive been using wordpress for years and this sis the first time i have run across this problem before, when i upload images browser or flash it says
- Failed to write file to disk - i have never had this issue over 3500 articles written and never a problem before, this was working even this morning then all of a sudden out of the blue it starts doing thisZ??
I need help please i have read so much of the same issues but no solution has worked yet!

talk to your host, disk is probably full or corrupted.

Andrea i spoke with them last night and they said they have no problems on there end, they ran tests?
Also i used FTP and uploaded images fine this way although it does me no good.
Can it be anything else on my end Andrea, also thanks as always Andrea!

What's the upload space limit for that blog?

2048mb