Hello Greg and welcome to the forum.
I found your post located in the Vista Help and Support Forum and moved it to here. With the specs you've included I'm not sure why it was posted in the Vista Forum but anyway, can you take a look at the following three links. If the computer is truly crashing then you may have some dump files to share with us as well as other information regarding your memory configuration and other items captured by Captain Jack's SF Diagnotic Tool.
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Best wishes and thanks for joining our community.
Randy