I have been getting STOP 0x00000051 REGISTRY ERROR almost everytime I boot the computer up. At first the computer ran fine but lately it has gotten to the point where I can't even get into windows. I have formatted and re-installed everything several times using the latest drivers, etc for everything and I still keep getting this error which leads me to think that it may be a hardware issue. Does anyone know what it may be? Could it be that the hard drive is bad? I have tried to use windows repair and have tried to reinstalled windows but I keep getting that same blue screen error. Here is my specs: 4 sticks of 512 Kingston RAM 184- Pin DDR SDRAM DDR 400 (PC 3200) ATI All-in-wonder 9600xt ASUS P4S800D-X Socket 478 SiS 655FX ATX Motherboard Intel Celeron D 310 Prescott 2.13GHz Socket 478 Processor Model BX80546RE2130C Western Digital Caviar SE WD800JD 80GB 7200 RPM 8MB Cache SATA 3.0Gb/s Hard Drive Windows XP Pro

This may help: http://support.microsoft.com/kb/815265

Try resetting the BIOS and use only one stick of memory. Have you tried Safe Mode?

You have not provided enough info. The message you got usually also has something after that error you quoted. If you search the Microsoft site using: STOP 0x00000051 Windows XP or similar, there are all sorts of "hits" and solutions, including the one Grok Loster pointed you to: http://support.microsoft.com/kb/815265 If there is more to the error message than what you stated, try to find a "hit" that also has that part of the error message in it.