Samsung Hard drives disappear or appear empty

A few weeks ago I got 2 1.5 TB Samsung HD154UIhard drives. I've noticed that these drives will disappear from the Finder. Sometimes I can see them, but they appear empty. Other times they will be there on boot up, then gone a few minutes later when I check my desktop. If I use a tool like System Profiler it can see the drives in there, but there is not any information after the Bay number like volume ID, etc. Disk Warrior and Disk Utility can sometimes see them, but not always. Also, sometimes on boot up Finder will tell me the disk is empty and ask if I want to ignore, eject, or initialize.

I did upgrade to 10.6 and that is when I started to notice the problem, but I can't say for sure it is a SL issue. It is ONLY these two drives, both SAMSUNG HD154UI. My WD and Seagates are fine.

I did move one to an external case and since doing that both are behaving. However still not confident using these drives. I saw on Newegg that someone had an issue with SL not seeing them after a time and getting the 'not ejected properly' warning.