Dell XPS

I purchased a Dell XPS 600 in February of 2006. Everything has been running great until about a month ago. I received and error when booting that said my PATA-0 and PATA-1 ports could not be detected (those are my dvd drives). I can still boot fine into windows but the drives are totally undetected by both BIOS and windows. I have tried formatting and BIOS is flashed with most up to date version. To make matters worse sometimes when I boot I get the error that my SATA-0 and SATA-1 ports cannot also be detected (the hard-drives) which leaves me unable to boot into windows. Usually letting it sit for 10-15 minutes allows me to get back into windows, but the dvd drives will not be recognized no matter what. I have tried swapping cables for all four devices as well as using other ports on the mobo, I have also tried the drives in another PC to verify they are in fact working. When all four devices fail to be recognized I get an error: Previous boot attempts failed at checkpoint [Bye] contact tech support blah blah. It is currently out of warranty so I am not sure what to do. I thought it may be the motherboard but I can not figure out how to get a replacement as I do not see one offered on Dell's website and I am not sure which one will be compatible with my current system. Thanks for any ideas/help you can come up with.