Set treeView_PopupMenu suddenly failed (vba); cured by re starting windows7. Nasty shock - seek advice re explanation/prevention.

Hello,

In Excel 2010, I have recently built my first TreeView popup menu which enables procedures to be called when right clicking a tv node from a UserForm TreeView control. All was going fine ...

... Suddenly, earlier file versions (that worked well on previous days)  FAILED at the following step:

Set treeView_PopupMenu = Application.CommandBars.Add(name:="UserForm1Popup", _
                                                 Position:=msoBarPopup, _
                                                 Temporary:=True)

Blood running cold - I re-started Windows 7 - and the problem disappeared.  
I have no clues re the failure, but does the evidence suggest the cause was outside the excel piece?

Has anyone had this experience? My piece is intended for distribution. I hope to understand what happened, to head-off the problem if possible, or arrange for a less disconcerting crash.

Can I do better than put in an error trap that directs the user to restart the computer?

I have continual AVG anti-viral cover. I carry our occasional checks with SuperAntiSpyware  (http://www.superantispyware.com/downloadfile.html?productid=SUPERANTISPYWAREFREE), but it was not on when this occurred.

I had to restart my PC yesterday because my old Logitech cordless mouse failed to drive the cursor (though it had a new battery).

The machine is not used for games/ TV, just work. My browser is google chrome.

Thanks
Kelvin