Dear Karl,
I use a Mac G5 (Dual 2.5 GHz PowerPC) and Mac OS X v 10.4.11. I indicated that I had dumped and reloaded AC v10, but I should have said AC v11.
I've tried three different keyboards with no change and my shift-click and command-click functions work in other programs.
Upon reloading, both functions worked for a short time, then quit working. Holding the shift key while drawing a line, for example, also doesn't work.
Thanks for your help.
Jim