it may be many things!
the power where it's connected!
diferent digital signals not having the same resolution... the drivers on your computer...
try recording other things! select to record what you hear on the computer and record a track! if you still hear the clicks you'll know it's from outside!
try connecting the edirol and the ub802 to different power sources!
i'd bet if you get a power stabilizer you'd be fine!

Is the "cracking" you're hearing at the loud parts - could be clipping - in which case all your knobs might NOT be adjusted correctly.

.......

i got some new cables, and tried switchin' things around, like the power sources and stuff, but when i'm recording my vocals they still skip. Sounds like a CD Skipping somewhat. I tried recording it through sound recorder and it never skipped at all. I'm kinda lost...

try increasing the buffer in your software.
if Sound Recorder doesn't glitch - but your software does - I'd start there.