Partypooper,
I'm assuming it's a 10GB drive from your info.
If you have 608MB of free space, that's going to cause problems.
Ideally you should have half the drive free, or at least a third.
You can't see hidden files and folders, so that's going to take up room.
Windows will take up room
Pagefile - your computer writes temporary memory information to this file and unless you clean it or tweak it, it's just going to get bigger and bigger.
MFT - master file table is allocated space for windows to boot up.
System Restore - there might be too many snapshots held on your drive.
If you really don't have very much on the drive, and it's this full, you probably need to clean it.
CCleaner from FileHippo.com is safe to use - beware of many others, they can cause problems.
Also right click drive C:
Select Properties and then disk cleanup
(it will probably take quite some time for a dialogue box to come up if you haven't done this in a while)
Finally, a dialogue box will pop up with check boxes, make sure all are checked.
Select the More Options" tab
Under System Restore
only click cleanup.
Hit Yes when it asks are you sure?
When it's finished hit o.k.
Finally defragment your drive.
Have a look at the space now.
It might take a really long time to perform some actions, be patient and don't think it's frozen, if you haven't done this in a while it could take up to an hour to complete. It should only take seconds on a regularly maintained computer 