I do not have any files hidden, but I cannot seem to figure out why the drive is showing as full.
No hidden files? How about the pagefile or the hibernation file? Also, all the system restore points? If you don't use hibernation, turn it off. This will remove the hibernation file which is usually the size of the installed ram in the system. Disk cleanup has an advanced tab where you can delete all but the last system restore point. You can also change the amount of disk space reserved for a page file and system restore points.