Post your machine, OS, video card etc specs with as much detail as you can for this kind of problem, hopefully in your profile section so it always shows.
Especially for this kind of issue.
It might not be AC.
In the other post you mentioned 'flickering', did that just start?
Any other anomalies?
Is it a laptop? If so, did it get hot?
lec
ps
Your other post is here; which you might want to delete,
http://archicad-talk.graphisoft.com/viewtopic.php?t=30224
which I answered first.
It's midnight here now and my brain is melting.
Gotta go.
Good luck.