I took Driven's advice and reached the SU folks. They confirmed the direction of this thread:

"As you may know, network licenses of SketchUp Pro no longer revert to the free version when you have exceeded the use of your allotted amount of network seats.

Each situation is different and there are always different ways of satisfying each individual need.

You have the option of adding additional network seats which would give you more room -- as well as more users -- to operate on your existing network.

You may also be interested in converted your two-seat network license into two individual licenses; individual licenses allow you to run multiple instances of SketchUp Pro on the same machine without receiving the error message you're receiving now."

Thanks, Dave R -- now I follow Driven's distinction about the limit on network licenses (which I should have said applies in my case)

But this still seems to be a problematic change for SU8 M2 because previously unlicensed versions would automatically open when the network limit was exceeded.

Right - it seems that it's not possible to have the professional and free versions working side by side. I found this comment (here: http://www.google.com/support/forum/p/sketchup/thread?tid=23077b23e79c7266&hl=en ) posted by a google employee:

"The Free installer will overwrite any Pro installs that you have– it isn't possible to install both Free and Pro side-by-side on the same system. We have implemented a new system to support offline use of network licenses (which I think you'll like) but you'll need to add to your network license if you've got more users than your current license allows."

This strikes me as a significant problem. For example, if I want to inspect or edit a component before loading it into my primary model, I need to close down. If the model is large and takes a while to load, this can become a huge time sink. Will folks really need extra licenses to do this?

I would be grateful for any workarounds. Thanks!

I understand that with the new SU8M2 it is not possible to open the free version once the licensed limit is exceeded. Since it is only possible to have one SU file open at once (or?) this makes it very inconvenient to cut and paste from one model to another. Is this really no longer possible? Thanks for the help...

@gaieus said:

Also, even if I only have one scene in my model, I use a template that will display the scene tabs so I do not get messed up by having them or not.

Do I understand that in setting your aspect ratios, you've accounted for the area used by your toolbars?
Thanks-