UPDATE:

Today I logged into both Professional and Basic.

Did not attempt to update either one. Made no changes to my problem client files.

Tried to e-file the returns that were getting rejected yesterday for error 54 (ProSeries not up to date)

All went thru fine.

So it appears to me the problem was not in my PS application nor my client files, nor my computer - but something on the Intuit end when trying to accept e-files. It appears they have corrected that as now things are working fine and I did nothing between yesterday's attempts and this morning (except a few bourbons!)

Thanks to everyone who offered suggestions and help.