Setting the (vla-put-MtextBoundaryWidth) value to 0.0 does work, after I rebuilt the block from scratch.
My concern is that I cannot recreate the problem that this resolves. The block that caused the original error must have been corrupted somehow in it's creation. And of course, AutoCAD crashed shortly after my original submission so I cannot examine the "corrupted" block.
-OR- (and more likely)
I did something idiotic over and over again that sent me in search of a solution to a problem that did not exist.
Sometimes finding that stupid thing I did, but cannot recognize, is the very hardest part of coding. And with everything working, and not knowing the REAL problem, it's bound to come around and vex me again!
Regardless, Thanks PKENEWELL!