Blank Error message shuts down PC???

[Dragon]

on my older machine - right before i logged in i got an error message - no X in the right hand corner to close - no text - just the buttons yes and no - and the caution sybol (yellow triangle with ! in it) whether i clicked yes or no it logged me in to my system. the fourth or fifth time i clicked no (inconsequencially) and it logged me out of my computer - and so it went from that point - whether in safe mode or normal logged boot or command prompt - nothing io tried could log me into my system . i remove the hard drive and put it in my other computer. i proceeded to make another HD with 2 partitions one for each PC - ididnt get the error so, i thought nothin of it.

now however it is appearing on another computer (temporarily on the same network, though sometime ago) any ideas or simila experiances anyone? plz help!

It sounds very much like a worm.. either that or your doing something wrong ..installing the software. I had a worm that would shut off your computer.. after like 2 min. Very big pain in the ass.. since I had to remove it manually..i guess that's what i deserver for not using av