Graeme--thanks for the your suggestion. I have narrowed it down to Tools > Options > Languages > Database Languages > PL/SQL > Adaptive Formatting > Keyword case. If this option is checked, anytime I try to add a two character key word (such as "AS", "IS", "OR"; three or more are fine!), it locks down.
I tried the -sc command line option as you suggested. After going through the basic setup, I re-associated the *.pks and *.pkb file extensions with the PL/SQL lexer and tried the two character key word. It worked. I checked the Adaptive Formatting > Keyword case option. It was checked. So....not sure what in my setup is causing VSE to lock up, but I can live without the Adaptive Formatting. Can't live without being able to type two character key words in PL/SQL!
- Pete J.