I just had a disturbing event with my turbotax session being interrupted with me logging into mint, and then my turbotax details being replaced with my mint credentials!

All intuit sites  are designed to use a single login identity.  If you have a different user account name for your mint account then for your TurboTax account  things may get confused. Make sure you log out of your mint account, not just change pages, and you may also have to delete your web browser cookies and caches.  Then you should be able to log into your TurboTax account again.

The same thing is happening to me but with my intuit self employed quickbooks account. The defaults to me entering my billing info and I can't undo it.