Disk read error.

[Welsh cake]

Make sure the computer hasn't got anything in the DVD RW Drive before you resort to a complete rebuild.

You'll be amazed by how many people who've forgotten they've left a disc in there that's stopping the PC from booting up.

[Creed of Heresy]

Much appreciated for the info, guys [and girl]! I'll run through those and see what happens. I also bought a new CMOS battery, because the computer is a bit on the old side and it seems to only have problems when it's been off for any period of time...whereas if it's shut down and then started up after it seems to start working again within a short time frame of being shut down, it doesn't have the issues...but it DOES after some time passes, so...I dunno, I was figuring it could be the BIOS resetting and reading the drive wrong...yeah, I'm a novice at this shit, I usually tend to throw spaghetti at the wall and see what sticks when it comes to computer repair. Also, the hard drive is an SATA.

[Tiberius]

That wouldn't be the problem if it's happening on and off like the OP suggested. If there was a bootable disc in the drive, it would try to boot every time. It would also require the BIOS to be set up to boot off an external source first, which is unlikely in a normal computer setup. Usually the HDD is the first in line.