Hmmm... as I mentioned in my post above, I am indeed using  PerlModule Apache::DBI. Maybe I tinkered above (too smart for my own good) trying to cache the db handle. Now I am trying with just plain my $dbh = ..., and things seem to be working.

One other thing I have done now -- I have turned off transactions. My db handle is now created with AutoCommit => 1.

This is really unreliable. I have no idea what caused my app to start puking and croaking yesterday, and what caused it to start working today. I have become too dependent on SQLite (and for good reason -- it is a great db store), and I really don't know of any alternatives. Any suggestions? I could try some of the key-value stores such as MongoDB/CouchDB, etc., but it would require learning a whole new paradigm, and writing new code for retrieving values (is there a DBI interface to a key-value store? **) While I do use PostGres for the bigger datasets, SQLite seems perfect for serving as the Session store, and user accounts and such.

Update: Hot damn! DBD::DBM