I really don't know anything about it, but I googled the error message and found this blog with some ideas to look at:
http://www.judahfrangipane.com/blog/...file-io-error/
ETA: Here's a thread from vbulletin.com where someone was having the same error. Apparently their problem turned out to be the use of FastCGI on the web server. There were other threads mentioning that error, you may want to search over there and see if you find anything else.