Finally got through to second-tier support on telephone. Spoke w/ 'Michelle' (apparently a different Michelle), who not only seemed to know what she was talking about, but also solved my problem. Per her suggestion, I saved my completed returns (TAX file) to a place on my directory I carefully noted. I then uninstalled TT, rebooted the computer, then reinstalled TT from the CD, and voila, the auto update worked. After that, the TT program did not ask me to update again before successfully doing the error check.
Lesson learned: TT will not do an error check unless you have successfully done an auto update. Manual update will not get you around this quirk.
In any case, thank you for your suggestion (even though it did not work). And thank you to the first-tier support rep who knew enough to know I needed second-tier support. (On my first call attempt to get help from support, the rep basically said he could not help me beyond the manual update suggestion, and did not offer to connect me w/ second-tier support.)
