D_Know_WD :
Hi there LumpyMushroom,
It is highly possible that there is some physical issue with your drive. You need to go to BIOS and see how is the drive recognized over there. If it shows as 74.43 GB, I would say that this may be the case.
If it shows as its full capacity, it may be a good idea to attach it to another system and see how it appears over there.
In case the drive is still under warranty, you can contact the manufacturer.
Cheers,
D_Know_WD
I'm going to agree with this assertation but am going to expand on it. That drive, in total, is 75 GBs large. I can't even remember the last time I even saw one that small and it must be quite old. Chance are high that something goes wrong with a drive like that.
As D_Know_WD said, checking it in the bios and running it in another computer are two ways to determine it's statues. In addition to that, running check disk might also fix the issue.
http://www.tekrevue.com/tip/how-to-scan-fix-hard-drives-with-chkdsk-in-windows-8/