12 Computers For Christmas
IF U UPGRADE RAM FROM 512 MB TO MORETHAN 1GB SOMETIMES SYSTEM CONTINEOUSELY RESTARTS WHY IS IT SO.
YOU HAVE BAD RAM. Seriously lay-off the Caps Lock. Try it with MemTest86+, most likely you have to rma/claim warranty on the stick you are adding.
Bad RAM or bad BIOS config.
Also, you need to have the same brand and model of memory. 2 different sticks can give you quite a headache.