RAM Issues

As the title says I am having a ram issues with my laptop and have tried everything I can think to do.

Laptop - Gateway ML3109
http://support.gateway.com/s/Mobile/2007/Apache/1014550R/1014550Rnv.shtml

The only difference is that I am running Windows XP Home SP3 instead of Vista but I had the same problem with Vista.

The problem is that my laptop will recognize each individual stick in either dimm slot and will run fine but when I run them together the computer will only recognize one of the sticks and will crash. I have run Memtest on both sticks in both slots with it reporting no errors with either stick.

I'm using two 1 gig sticks of PNY DDR2 667 bought them at the same time and they work in other laptops together just fine.

The Bios doesnt doesnt show the individual slots but the memory as a whole. There is not a Bios update on the gateway site but I am running PhoenixBios 83.09.

I am really not sure where I should go after this but I would appreciate any help!

Thanks