No, that's NOT normal...something froze it up.
Checkdisk on a 500G drive should still be no longer than an hour or so, and that's if it finds things that need doing as it doesn't check the entire 500G's, only the used space and MFT.
Giver her another go and see what happens. You can also try Michael's suggestion to run it from a command line with admin privileges, that may help but if it goes longer than a few hours then pull the plug again and let us know what happened. Maybe also check your Event Viewer and your CBS log for any info. The CBS log can be found in Windows\logs\CBS\CBS.log
It can be rather large, like 60MB plus so check the Date Modified info because it could also be logged in the smaller CBS.persist.log file. Notepad can look like it freezes up opening this large a file so use Wordpad instead. Or if you have a 3rd party program like NoteTab Lite (free editor) that's even better. Scroll to the bottom and look for the time entry for when you ran chkdsk and see if there's any info on it...there should be.
