2016 Mechanical Locking Up When I Run Global Find/Replace

I'm running 2016 Mechanical here and there's something I've noticed which AFAIK was not happening several weeks or months ago. When I do a Find/Replace AutoCAD just goes silent. The dialog window no longer responds, in fact nothing responds and I have to use Task Manager to shut it down.

Another quirk is that sometimes when I'm using the IDE for LISP the program goes 1/2 responsive. The LISP code is no longer running (the green and yellow arrows in the tool bar are ghosted) and I can change windows in the IDE but when I move the cursor over into the AutoCAD window there's nothing. The cursor disappears and again the only way to get out of it is with the Task Manager and crash dive the whole operation. It's weird because I can usually save the LISP file(s) but I can no longer operate anything in AutoCAD. Trying to click the X in the upper right-hand corner is also useless.

Tomorrow morning the IT guy who has Admin rights is going to apply the two (2) Service Packs I downloaded today from AutoDesk to see if that doesn't clear things up. I also have HotFixes #1 and #2 at the ready but I didn't read anything about these which indicate they will resolve the troubles I seem to be having.

With that in mind has anyone else applied these SP's and/or HotFixes? Did you notice any troubles with them, etc...?

UPDATE: If I do the Find/Replace one instance or one sheet at a time, that is I use the buttons to step through the process it works. It's when I choose Replace All that it goes south. Or of you're in the Southern Hemisphere, north.

Oh yes, I almost forgot about full disclosure of these possibly unrelated points. This machine used to run AutoCAD 2015 Mechanical and that package is still installed. I don't ever use it and I recently changed the file association in Windows so that when I execute any DWG file it runs 2016 Mechanical. The other two AutoDesk related products installed on this machine are the 2015 TrueView and the client piece for AutoDesk Vault.

Applied both Service Packs this morning but it did not fix the Find/Replace issue. If I try and search the entire drawing it will lock up AutoCAD every time and the only way out is to kill the process with Task Manager. I'm afraid this is one of those issues that only a complete rebuild will resolve. Thank you again Microsoft for making life so simple.