Page fault in non-paged area

I started to get the above message. I do not know what is causing it. Further message is as follows: Stop: 0x00000050 (0xFFF7FFF8, 0x00000000, 0x8053434E, 0x00000000). Can someone help me solve this problem. Many of the programs on my hard drive are still working, but when I try some programs like system mechanic to clean the resgistry, the computer crashes and leaves the above message. Help? Thanks. MMN