When OnyX is running that kind of check, if the drive is large, or has a lot of files, it can take a really long time to finish, and during the process the spinner will appear. Just let it run, it will eventually get done. I waited about 4 minutes and it worked.

Mac OS X is famously stable, but that doesn't mean that you can just set it up and ignore it. One of my favorite third-party system utilities is OnyX. The Finder might slow down and your computer might seem to be unresponsive (freeze).

It's never done this before so I thought it was odd behavior. Come to think of it, I have a 1TB hard drive now on this newer mac.

I use to run onyx on a 250GB drive so that would explain why it's taking longer I suppose. Does seem odd that a program would do this sort of thing when running, like it's freezing. Tuxera. No other programs on my mac do this when I'm using them.