I'm getting problems trying to use a boot disk when i start my computer.
After it's done loading the BIOS, my A:disk drive didn't run at all. I have the disk inserted, but it didn't read the disk at all. The disk drive still works, but it doesn't at startup.
Is there something wrong with my BIOS?

Have you tried multiple boot disks? Or multiple disks in general? It sounds more like a hardware issue with the drive and not BIOS related. I'd also check the internal cables to make sure nothing became loose.