I realize that this thread is old, but hopefully others will find this information helpful.
We do have a knowledgebase article which describes this behavior with MVSETUP and how to correct it (at least the part about setting PICKFIRST back to 1). I'm not sure about the object snap settings, but I believe that problem was version-specific, and has since been fixed. .
The article can be viewed here:
Although the article specifically states that it applies to just a few products, this actually applies to any/all AutoCAD products.
I am currently working on Autocad Architecture 2012. I experienced this issue with my double click text editor getting disabled and my onsnaps getting cleared. I do recall using MVSETUP earlier in the day. I was able to restore my double click behavior with PICKFIRST setting on 1. I only lost two hours of production researching this topic in the forum. Why does MVSETUP alter the PICKFIRST setting? Evidently this problem has been occurring for a long time and still has not been fixed.
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