Screen locks even when plugged in
Solution 1:
Apparently it is happening because of a "screen saver" setting:
This is located in the "Personalize" part of the system options.
If you are on a domain, then network policies can be used to force the screen saver to be active. To see if this happening use the following command:
gpresult /Scope User /v > "c:/policies_output.txt"
Then examine the output file.