Audio becomes progressively more corrupted as I watch a video

[frumpett]

As I watch video -- either with VLC or on youtube or hulu - the audio starts off fine, but within seconds becomes corrupted. I can hear background noises of the video and music fine, but I cannot hear dialogue. Sometimes some of the dialogue comes back, but it is very faint.

Some of these videos were downloaded from the internet, so I cleared my cache on Firefox. I also went to Disk Utility and clicked on "repair disk permissions." Doing those two things have not repaired my issue.

What else can I do to fix this? Thank you for any help you can provide.

ADDING: I have shut down and restarted my computer a few times. Every time I do, the audio seems to be fine... for about 30 seconds, and then begins to get corrupted again.

 

[ScoobyMcDoo]

Have you tried playing the files on another computer to see if the problem persists there? Perhaps the files themselves are bad.

 

[frumpett]

Yes, I tried that. I transferred the files to a notebook computer which I keep hooked up to my TV. When I played the files there, everything was fine, including audio.

Also, in the last few days my computer keeps telling me at random times that it needs to be restarted. It happened twice four days ago and once every day since.

Honestly, it feels like I have a virus on my computer, but everything I read says there are no known Mac viruses, so I am legitimately confused.