Celron processor and compaq system
Estarting in between a programme

Hello,

my system is getting restarting while we are in a middle of something.earlier my ram was 256mb but now it is 512mb.ram is of DDR1 .when i am using the 256mb ram usually a blue screen will appear with some message.but now it is ok with 512mb. but still the system is restarting. what will be the problem