Hey there, Idczt87!
"The underlying task reported failure" is a very rare error, which indicates that your HDD has problems that the Disk Utility cannot fix.
If you can still access your drive, I'd suggest to back up whatever you can.
Afterwards you need to perform a Erase and Install of your MAC OS X on that drive, this will basically erase all your data.
That's why it's pretty important always to have a backup of it somewhere else.
I suggest you use the following articles as guides on how to perform these troubleshooting steps.
Resolve startup issues and perform disk maintenance with Disk Utility and fsck:
http://support.apple.com/kb/TS1417
How to Erase and Install:
http://support.apple.com/kb/HT5943
Hope I was able to help you!
Keep me posted!
SuperSoph_WD