Q:

Computer hangs at BIOS screen. Cannot enter setup

I have an HP Pavilion a6500f (it's a year out of warranty) and it's hanging on the blue HP BIOS screen. If I mash F10 while it's starting up, it will say "Entering Setup..." but I will see no results. It will hang there and not do anything. 
If I actually wait until I can see the screen and then hit F10, there's no response at all and the computer will sit at the BIOS menu. 
I've dusted and cleaned it out, reseated the memory, switched the RAM slots, and reset the CMOS battery using the reset jumper. I'm out of ideas. I'm pretty sure it's not a hard drive issue, since my problem is at the BIOS. After this post, I'll disconnect the hard drive and try to just boot without it. 
Anyone have any other ideas? 
Edit: 
Okay, so I tried disconnecting the hard drive and now I can get back into the BIOS. I reconnected it and I'm locked out again. So the problem is my hard drive.. I guess I should delete this post unless someone has any ideas as to what's wrong with the drive? 

A:

After the edit, it sounds like a device enumeration issue, something wrong with the hard drive probably. If you try swapping it out for another hard drive you know functions well elsewhere does it again stall?

Original reply:
If it hangs at POST it probably indicates a defect with a critical component (ie. not a component like the hard drive, but a component like the memory/mainboard/CPU). It sounds like you've done everything you can to try and alleviate simple issues with CMOS corruption/bad seating, so I would suggest there is an actual defect on the mainboard or a problem with device enumeration, there nothing to speculate any further than that.
Hope you get it fixed.

A:

Sounds like a device isn't being detected properly and it's hanging trying to enumerate it.  Probably, if you wait long enough (potentially 30+ minutes) it may eventually go past.  That said, since you unplugged the hard drive and it quit, it's almost certainly the hard drive.  It could well be a motherboard fault or something but it's unlikely.  The easiest test, of course, is to try another drive or try this drive in another machine (although note, other machines may be more lenient about their timeouts)

