YUP!  

I am/was? writing a large program, broken down to separate tabs and classes for its operation. Now, nothing runs.

Is there some documentation about this?
What am I supposed to do?

Should I abandon processing?
Is there someone trying to sabotage Processing?

If you want all the old imports from v1.5.1, go to preferences.txt, and find this item -> preproc.imports.list = 

I cannot get my classes working. I can go down the list and comment them out one-by-one, and the error happens on the next one.

widget_area area_main;
widget_area area_nav;
widget_area area_sampling;
widget_area area_tip;
....

I reinstalled my java, yet, find it difficult to believe that Processing could be so utterly broken.

Up till now, you haven't mentioned which libraries/classes you want to import.

The need to import non-blessed classes is here to remain, it is a clear signal, if you have to use import, that the sketch will not work in JavaScript!

brendaem, you are not clear, if the problem is about classes like HashSet, for example, or your own classes. You don't tell if you have error messages and what they are. In short, you complain without allowing us to help.
Perhaps you are just missing a closing brace or something.
" find it difficult to believe that Processing could be so utterly broken"
Indeed!

Something is defiantly broken. I tried, reinstalling older processing, reinstalling 32 and 64 bit java. Something does not seem right. It feels like, a change in Java broke something in Processing.

My home machine has not been updated. I will try it this evening.

Still no error messages nor useful information. You should be able to install v.1.5.1 beside the 2.0 version, and see if the problem is in your code or in the version of Processing.

Processing reported structural errors in the wrong class--even when they are in separate tabs. That was what was going on.

The syntax checker is bugged.

Not really. (Since it is the Java one, mostly, which is battle tested!)

PhiLo, I am sorry, it is indeed bugged.