C-driver properties

I'm not a novice user but I have a small problem that is bugging me (making me fell like an idiot really). Everytime I click on c-drive to check the properties, or to make changes, the program locks up and I have to end the process. Even when I am in Windows Explorer or in Admin - storage devices. All of my spyware, antivirus, updates, etc., are up to date and I have restored to a previous date a couple of times to no avail.
What little stupid thing am I overlooking?
Something else that just happened (this I can probably figure out myself shortly, but if you have a clue) my sound when I play a video, sometimes an avi or an mpg, is either non existant or sounds off-beat or slow.
Thanks in advance
Don

Thanks for the advice but I always test my anti-virus & spyware programs with 2 different applications each for confirmation. There is nothing else clogging up the works either. Even with only valid processes running & no programs running it does the same thing. Changed to another user I had setup which has absolutely nothing installed or going on with same result. Ran a program which checks files for corruption and/or changes to no avail. Have all current Windows security updates. There should be a setting in the registry which I can modify to correct this problem but I'm not sure where it is. I am quite familiar with the registry & have used it to correct many problems on my system & many of my customers. Have even ran a program to check validity of DLL files without any luck. Still stumped.

Sounds like it has got something clogging up the works. Just because your av and spyware programs appear to be up to date, doesn't mean that they are working. Viruses often change the appearance of av so it looks like it's working but it isnt.

Also you could have a badly fragmented drive, a corrupt page file, possibly 1 or 2 odd cells of bad ram. In order to help further, please post your full system specs and what av and spyware software you are using.

Oh yeah and clear out your temporary internet files - often the cache is set so big that it takes for ever to read it.