Interestingly enough, someone in the Real Forum led me to the solution: the
numeral 45 was somehow synched to selecting RealPlayer as the device for
playing CDs...so when I put 45 into AutoCAD (or as I found out later,
Wordpad, Notepad, just about any text editor), RealPlayer would pop up to
play a nonexistent CD; selcting Windows Media Player as the default CD
device did the same thing with WMP. So, just making neither program the
default CD player fixed the problem.
Most of you in this NG, on the other hand, were of no help at all. If you
had no constructive advice to give, why bother posting anything in regard to
my question? Your jerky, faux-clever jokes were lame and time-wasting...in
fact, if ever I have another question about AutoCAD, I imagine I'll go
somewhere where people are helpful, not geeky.