Question : Problem: Windows keeps rebooting until I un-install memory, suspect Windows updates.

BACKGROUND:
I have several computers that I maintain.  I've upgraded the memory on many of them..  Eventually, they would get into a state where they would just keep re-booting from the Windows splash screen.  I eventually traced this down to a problem with the memory, and removed some (Cutting 1G down to 500K, for example).  I do Windows udpates on a regular basis, and began to suspect them.  This morning I came in and a PC that had been working fine now rebooted continously. Updates had been automatically installed overnight.  I cut the RAM from 1G to 500K and it works fine, with the exception of being excruciatingly slow.
QUESTION:
Does anyone know which, if any MS Windows update would cause the above behavior?  

Answer : Problem: Windows keeps rebooting until I un-install memory, suspect Windows updates.

Ok, thanks for the feedback ...  incidently the 1st memtest that dbrunton was referring to was
probably memtest86+  v2.11 :
http://www.memtest.org/


If you're going to look into Minidump analysis then these three links will help>

A good article here>
"Windows system crashes":
http://www.networkworld.com/news/2005/041105-windows-crash.html

Analyzing Crash Dumps:
http://www.experts-exchange.com/Operating_Systems/Q_21585874.html

The ABC of Blue-Screen Dump Analysis:
http://blogs.microsoft.co.il/blogs/sasha/archive/2008/06/28/the-abc-of-blue-screen-dump-analysis.aspx