Computer help

On videos, it will play 2-7 seconds without sound and then freeze. Though, occasionally, it will continue playing without any sound throughout. 

On iTunes, it simply won't play at all.

If I restart my computer, it fixes the issue for a little while, and then it returns at random without any warning/signs/etc.

I've run McAfee, cleared my internet data/cookies/etc, and run a diagnostic on my C-drive drivers. No luck. Google has not been much help.

1000000 internets if someone can explain this to me.

Might not hurt to install and run Spybot v. 1.62.  And for free system/registry cleaning try CCleaner.  I have Auslogics Bootspeed which is something I purchased that roughly does the same thing as CCleaner but I think it is more involved.  I would recommend that as well if CCleaner doesn't do the trick.

Worst case scenario, back everything up, wipe the HD and start over with a fresh OS install.

My $.02 worth...