Can a badly grooved disc/pad cause 'grabbing' itself and the caliper be fine?

[Stuntman Mike]

My front driver side disc looks like a record. Pretty deep grooves -- the unworn 'lip' of the disc is about 1/8". Lots of mudding and general neglect has also left the vents in the rotor completely filled with dirt.

The grabbing doesn't happen until I drive more than 15 minutes at 55-ish, which I'm guessing it heats up and causes problems. It sounds like metal scraping and will sometimes grab suddenly without me pushing the brakes, resulting in a very dangerous pull towards the side. I'm parking it until fixed.
These symptoms also happened before when the fluid was getting too low, before I 'fixed' the leaking brake line. Fluid is still full and has been for months, so that's not the issue.

So, can the excessive deep-grooving itself cause the problem without the caliper needing replacement?
I am going to get a new rotor and pads but what's the likelyhood of the caliper being junk in this situation?

Money is tight as always. This was a $350 truck to begin with and I've put less than $100 into various repairs including the rear differential, so please no "replace everything" lecturing.

 

[Jspafford]

Have you pulled the caliper? Could it be that there is a rock or something stuck between the pad and rotor that is randomly grabbing onto the rotor as it spins past?

I would pull it apart, you can put it back together without having to replace anything.

 

[martin]

check the wheel bearing.

 

[Stuntman Mike]

Update: Fixed things, rotor was cracked in 2 places, and yeah the inner wheel bearing was bad also. The cage was torn apart and the rollers fell out. Still kept the old caliper and everything is fine now.