BleepingComputer.com: Goofed up adding RAM, now PC won't enter windows

My PC has two DDR DIMM slots, the first one filled with a 256 MB and the second one empty. Today, I bought a 512 MB to put in the empty slot. Unfortunately I made the mistake of taking out the 256 MB card from the first slot and putting it in the second slot while putting the new 512 MB card in the first slot, thinking that the better card should be in the first slot. Anyhow, upon startup I got a momentary error message saying something like "C:$Mfst could not be saved. The operation failed" Now, my computer refuses to enter Windows. What should I do?

I no its a stupid question, but have you changed it back, or taken out the new one and just put in the original, and see what happens, also i have always match them, like 256, 256.

If changing them around don't work just clear the cmos and see if you don't have better luck. Also make sure the ram chips are set right.

My working original configuration:

Slot 1: 256 MB
Slot 2: Empty

My failing first new configuration:

Slot 1: 512 MB
Slot 2: 256 MB

My failing second new configuration:

Slot 1: 256 MB
Slot 2: 512 MB

I will post what happens when I go back to the original configuration.

PhatCat, how do you "clear the cmos"?

Usually to clear the CMOS you need to disconnect the power supply, remove the battery and then it's usually a jumper that needs shorting near the battery to clear it.

Consult your motherboard manual for more details.

Is the second ram chip exactly the same specs as the first (the one that works)?

Will it work with just the 512 in the first slot with the second empty?

If it has hyper-threading technology the two chips must be exactly the same (size and type), and matched.

With the original configuration (the 256 MB card in the first slot,) I got the same error. The error I keep getting is:

UNMOUNTABLE_BOOT_VOLUME

followed by some text recommending that I fix the problem somehow, followed by a line saying:

TECHNICAL INFORMATION:

followed by some data looking something like:

0x0000000000

and so on and so forth.

Post the full string of the BSOD

0x00000000 (0x00000000, 0x00000000, 0x00000000, 0x00000000)

It will give some indication of what's causing the problem.

If it's this STOP 0x000000ED (0xaaaaaaaa,0xbbbbbbbb,0xcccccccc,0xdddddddd) UNMOUNTABLE_BOOT_VOLUME read the following MS Article

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