I had the same problem a while back "the cdrom drive wouldn't open up and stay open" It was driving me crazy as I attempted to put a disk in the drive before it closed. It was too fast for me, it would grab my hand before I could get the disk inserted :) Once I removed ATA/ATAPI/MFM/RLL support from the kernel and only used Serial ATA and Parallel ATA drivers It worked fine again.

< > ATA/ATAPI/MFM/RLL support (DEPRECATED) --->
<*> Serial ATA and Parallel ATA drivers --->

More info;
http://bugs.gentoo.org/show_bug.cgi?id=319829

May be worth a try ...