Thanks for responding Bob & Skywalker
I got zero errors after running memtest
An hour later while using Quicken it again shut down
without warning, no error msg - nothing - instead I got a
black screen. It restarted and the damned 'critical error'
msg came up asking if I wanted to send an error report to
MS. I do not know how to intrepret the report.
One other person asked if I over-clocked - I do not know
what that means muchless to correct it.
Any help for a complete amateur is apprciated.