Can anyone here explain this to me a little bit? I guess i'm not 100% clear on what this uninterruptible sleeping processes thing is.

I get vzrmond alerts every few minutes from our server saying that unint > 20, then another that says unint is ok. I also get loadavg > 30, and loadavg is ok. I know I can change these default numbers in the vzrmond.conf file, but I want to know why I'm getting them, and if it's a problem I should be worried about! Does anyone have any experience there?