lsass.exe can't read memory

[Josh McAdams]

A message box with the following text keeps popping up
when I boot up my computer. If I hit 'OK' to terminate
the program, I get the XP Home login screen, but with no
user profiles listed. If I hit 'Cancel' to debug the
program, the computer just sits there.

The last time that I booted up, I was not connected to
the internet and didn't install any new software.

Any clues how to get past this?

----------------------------------------------------
lsasse.exe - Application Error

The instruction at "0x77f7ecd5" referenced memory
at "0x000000c5". The memory could not be "read"
----------------------------------------------------

Thanks,
Josh McAdams