Trouble in River City...

Computer worked fine last night
Computer worked like crap this morning.
Lost a bunch of stuff.
Rebuilding
Rats

Update: I've gotten most of my functionality back, but lost about 6 months of email. A strange problem I haven't seen before.

All of the Admin accounts are restricted. I need to "runas" using the same account to get full access. So everything works, but there is always an extra step in there now.

Fixed it:  Somehow my .EXE file extension had lost association with the reality that it is there to run applications.  The EXE category had completely disappeared from my "file types" in folder options.  Strange.  As soon as I added EXE with an association to applications, everything came back.  I've never seen that before.  The whole runas thing with it's levels of disallowed and unrestricted was a red herring...altho the runas did let me use the computer for a couple of days until I had time to figure it out.