This is not my pc in system specs but this one: Processor: Celeron 333Mhz Mendocino Graphics: Nvidia Vanta 16MB (AGP) Motherboard: Soltek SL-62C Sound Card: Aztech AZT 2320 (ISA) The motherboard has 2 slots for RAM and they only recognise 128MB each. Due to lack of parts, I had put in one stick of 512MB PC133 SDRAM. The computer worked fine, the only 'problem' being that it recognised only 128MB RAM but I couldn't do anything about that. Now I managed to get hold of a 256MB PC133 SDRAM, and put it in the second slot. The computer POSTed, showing 264MB RAM. Great.... but my happiness was short-lived. Windows didn't load. I got the message: I pressed the reset button to see if it happens again, and this time I got: So I decided to repair windows, but I couldn't get Windows setup to run! . So far it didn't cross my mind that my 2nd RAM module I inserted today could be the fault, because the messages I got mislead me into thinking my XP got corrupted. However, I removed the 256MB module and the pc worked normally once again. What I wanted to know is, is there any way I can get both RAM modules working together so I can get at least 256MB total (128+128) on this pc? If I can do anything it's only through the bios since I can't get in XP with both ram modules inside the pc. Could I have got the wrong RAM? Both 512 and 256 modules look exactly the same (168 pin, 2 notches, 3.3V), and both fit in the slots.