What did you do that makes it able to paste and attach files again?
Looking at your Process Explorer log I see the top program is Windows Live Mail. This is a rather obsolete program that is no longer being supported. I also see a lot of Mighty Text entries. I wonder if a third party program might be at fault? It doesn't appear to be running out of memory tho.
Run Process Explorer again and click once or twice on the CPU column header to get the big CPU users at the top. Sometimes if the CPU gets super busy you will get not responding errors. If you wait long enough it usually comes back.
About the registry search results. You could go into regedit and delete the msaud32_divx.acm values associated with the two keys it found. I would export the keys first but I doubt that the system will notice when they are gone.