What Operating system is it XP?
What happens if you turn it back on, do you get the same thing?
Sounds like a blue screen crash, try and see if you can see what it says, if you have a 'Pause' button on your keyborad that might hold the screen so you can right down error
What rojash said was curt, but you did say "cant remember what else was said" giving the impression you did not bother to read it or make a note of it.
If you had said "the message disappeared before I could read it", or even it was your daughter using the PC, maybe we could understand you not having details of the messages.
So, what happens when you turn it back on, same message? Sounds like it might be a re-build, this means that you will probably need to re-install,do you have anything installed on it that you need documents, web pages etc?
I think with XP, you can try and repair by the CD ROM