you can boot your computer into safe mode... and disable the automatic restart after BSoD.
if it crashes again. write down the error code. which would be helpful in identifying the problem.
that being said. it's hard to know what exactly is happening to your system. smart move would be to back up any important data you have on the machine in case it really gets damaged... which can happen with persistent crashing.
messing with the registry is never really a good idea unless you know what you're doing. the registry is basically a database of all settings and associations within the computer.
so it's likely, something was edited out of the registry, that somehow has left a dependancy in some sort of media player.
you could try uninstalling all media applications, and reinstalling them. ..web browser, flash, adobe, media player, quick time ...drivers for graphics, sound, display.
download and run a memory test utility. run chckdsk on the hard drive. defrag the hard drive.
errors from sleep mode tend to point to me to a mixed up boot sector. can also... just run a fixmbr routine...with an install CD. although.
the error code from the system crash would give you a better idea where to start. it'll identify the component, or memory module that's causing the error/crash.
also... in general. spyware, and anti-virus scans are always a good thing.
my honest hunch... would be dying RAM. might explain the odd buffer in the speakers. if the system hangs. or crashes. it's normally either CPU or RAM. ...unless something serious has been done to the registry. programs would not function, not crash the OS.
...although, like i said. back up your stuff. a reinstall of windows would solve the issue altogether if it's registry related.
a mem-test (windows 7 comes with one i'm pretty sure) may isolate bad RAM.