active audio devices????

i am having a problem with the lack of no active audio devices, i have made
sure that all of the drivers are loaded and working properly for all
hardware, but still no dice. i have also run chkdsk and recovery from
original os disk, but still no dice. no adware on my pc and no virus. so i
know that all software is working fine but when i select volume controls i
get the famous,

"there are no audio mixer devices available. "To install mixer devices," it
says, "go to Control Panel, click Printers and Other
Hardware, and then click Add Hardware."

my problem that i have found is that it is not hardware, to my best
knowledge. so this is really starting to make me lose my patience. i have
also read on this discussion that it could be sp2, but i doubt that. although
i didn't have this problem until i was updated with sp2. i also reformatted
my pc right before that and that was only about 2 or 3 months ago. i have
also defragged since then.

what is really interesting is that it all started with my speaker setup
would change from 5.1 to 2 speakers all by itself, so question 1, what would
cause that? question 2 is how would it graduate to a more serious issue from
that and why?. i know i am not dumb enough to erase anything, one of my
roommates might be though! either way, laying blame doesn't make a solution.

so after that long winded explanation, is there anything that i am forgeting
that might be of some use, cause if so you will be my new hero of the week!!