Need help, please!!

I don't know what happened, I rebooted my computer and it wouldn't even POST, so I started checking things and figured out it is my RAM slots. If I put any of my 4 dimms in either slot 1 or 2, the computer won't post. If I put those same dimms in slots 3 or 4, the system boots. I have tried clearing the CMOS, that didn't help, I don't know what to do. What do you think the problem is?

I really need help with this one, any info would be appreciated, and the mobo is a P4P800-E Dlx.

Me thinks your ramslots are toasted. Time to RMA.