Man - you do have some issues (sorry, probably not what you want to hear)...
I'd say you just had issues with the 1st PC, but you said you put it on a second PC and still had issues - that makes me think it's a problem with your Acid install files. Can you get your hands on a different Acid 8 or 9 disc? If you can, I'd re-install from that. Maybe Sony's tech support can ship you another disc? If you put it on a 2nd PC and had the same issues, that rules out the OS, and any PC specific hardware issues (I'm assuming the soundcards, etc.. are not identical on the two PC's)
Are there any common links between the two?
Are you using an interface or the PC's soundcard? If you're using an interface, the issue could be with that...
If all else fails - I mean everything else fails, try the steps below. It's not simple or fast, but as a last resort, I'd do the following...
(get ready, this will take hours)
Get ALL your stuff (samples, midi's, songs, acid files, synths, VST's - everything) off the PC and put it on a USB drive
Reformat/reload the PC (Windows and everything)
Do any and all updates to windows
Reinstall Acid (redownload the files if possible)
Check for any Acid updates
Put all your stuff back where it was
have a drink/smoke (I'm not condoning, that's just what I would do at this point in the process)
cross your fingers and try again
Good luck man