Alright, I ran a defragging program called PerfectDisk. It found some errors, apparently, but overall did nothing to fix my problem.
I am not quite sure what you mean by "fdisk", Ryex, but here's what I did instead: I went to Computer and and then I checked the properties of my C: drive. I went to tools and then clicked the "Check Now..." button under "error-checking". At the end windows reported that "No problems were found on the device or disk. It's ready for use."