I just bought a 256 SDRAM PC133 stick. I already have one, 128 SDRAM PC100. I stuck in the 256 and started my computer. The compaq screen came up and in the top left it was counting the memory, ( up to 384) it got to 384 and said "164 memory error" and gave the memory adress. from there it did something and asked if i wanted to save the changes. I didnt know so i clicked yes. Then it whent to an options screen with such options as Start in safe mode and stuff. i clicked start in safe mode. It did and i checked to see if it was in there and it was. So i restarted and the same thing happened.