But if I re-index my Q 2006 file, trash my Quotes file, then import it into QM 2007, the 'corrupt data error' comes up.
I did find something interesting in my systematic search for a cause, and that is that when i install it on my Snow Leopard machine, it works fine with a new, unpopulated data file. Now perhaps it's accumulating some ancillary file that doesn't get trashed, but I can't run that down. The Quicken 2007 is a fresh installation, each time I try out a new approach, I reinstall the software.
I'm convinced it's something about my Lion installation that's the cause, since others as yourself seem to be OK-although I haven't been able to run it down.