Can Bad ram do this?

I have 2 PC2100 samsung DDR ram sticks, and when both are in, I get random restarts on my comp. When I take one of them out, they system runs fine...is it a bad stick of ram? they are both 256MB

Put the other one in a pull the one that gives no problems out and see what happens.
Over aggressive memory timings can also cause this if both work fine alone.

Are you overclocking the fsb? Many people have had several sticks run fine at a high fsb individually but together they couldn't keep up the pace. Also it could be your board. Do you have extra slots to test the memory in?

Uh-oh. Sounds like my comp before I ditched the RAM. Find a blank floppy, then download and run this program from bootdisk.com. It'll make a boot disk to test your RAM. I'd consider 3 successfully completed loops of the burn-in test a pass (I've had bad RAM pass one loop, but never two). If the program pukes or freezes or anything bad more than once, kiss the module you're testing goodbye.
Make sure to test each stick separately.
Good luck.

While docmem is good be sure to test with defaut fsb and slow memory timings as your ram will fail tests if the timings are too aggressive or overclocked.

The only real way to test memory without any system influence is to use a hardware memory tester but they cost over a grand.

I have not overclocked and am runing 133 FSB. I took out one of the sticks, and now I am not having any trouble...time to file for a refund form