Problem solved. 

 

A - too simple error - in the properties window, where the color switch was set to blocks, rather than layer.  I never use 'color', only layer, so pay no attention to it.  I must have stumbled over the switch.  I crawled through all sorts of discussion of layer lock before I found this. 

 

There are, of course, lottssaa ways to go wrong, and I'm careful to avail myself of many of them.

 

Thanks for your help.

 

Enjoy    /s/   Bob 

The Dell 'third world help' was not much help, but I thank you for yours.

For now, I'll just plot from my old computer, and give the plot/win7/HP755cm a rest.

New problem: Unable to control layers for new work. Old blocks change layers OK, but new lines -- blocks are locked. I've been all over the 'layer-lock' stuff, but I'm not clever enough to find a way to fix my problem.

Any ideas? Or, should I best post as a new topic?

 

Thanks   /s/   Bob

I'm right now on an interactive chat session with Dell technical support.  Can any one direct us to an address for a driver which we can install???? 

 

Thanks   /s/  Bob