XP Won't Load with additional RAM

Pentium III, 450MHz
128 RAM in Dimm 0 (1 & 2 are empty)
RAM expandable to 768
Intel Motherboard SE440BX-3
Phoenix BIOS 4.0 Release 6.0
XP Home Edition

I am trying to add another 512 RAM (one stick). At boot-up the BIOS recognizes the additional RAM and shows new total RAM correctly. XP however refuses to load. It says FASTFAT.SYS is corrupted. Prompts you to restart Windows and at first screen press "R" to repair. But when I try to do this, there is no response at all to the "R" key being pressed. I keep ending up on the same error page, unable to proceed. When I remove the additional 512 RAM, XP loads just fine again.

I have tried the following:
Checked that both RAM sticks are PC100, two sided, etc.
Tried installing the 512 in Dimm 1 and then in Dimm 2. Tried switching the 128 and 512 into different Dimms. Tried removing the 128 and only using the 512.

Since it won't let me Repair, I replaced FASTFAT.SYS in the drivers using the XP disk. The path is: C:Windows/System32/Drivers. XP still wouldn't load. Same message about FASTFAT.SYS being corrupt again.

I have tried adding the 512 and then reinstalling XP but I can't get through the install. I got an error message (I'm sorry I don't remember what that was).

In the midst of all of this, whenever I have removed the new 512 stick of RAM, XP loads and works properly again.

I don't know what else to try. Any suggestions greatly appreciated.


thealu

 

looking at your specs i think your mobo won't handle a single 512MB on its own, if you look at your mobo manual it should tell you the maximum ammount it will will take for each slot probally 256MB

 

You're right, max is 256. Can't believe it didn't occur to me to check that. Thanks so much for taking the time.

thealu