I have a TASKalfa 300 that keeps displaying "Self-diganostic Please Wait" and has an F248 code in the lower right of the display. Does anyone know what this means?

Sorry..never mind. When I went back there, the lady who was having the problem (who wasn't there the first time) said the machine only acted like that when they printed a particular file.
Anyway...an F248 code is an engineering code that signals, surprise surprise, a communication error.

I had a machine doing the same thing and the culprit was a user was printing to it using a Toshiba print driver. Changed to correct print driver and amazingly the problem went away.

I'd like to tell IT - "I told you it was the network".

i had this problem, when i called tech support they said it is corrupted data, so i start checking all the pcs print que, i found a job stuck in mac que, when i deleted that job,the code disappear. hope it helps.