i've had the same problem
my problem was that the update script got access denied when uppdating the plutocore and mythtv "access denied for firstname.lastname@example.org"
i downloaded a fresh .ISO (release .35) burnd and booted from it.
the installation partitioned the disk and atarted to coping files.
when it was time for the data base insert/syncing, mysqld crashed, the swap space was too small.
did a new installation and manualy partioned the hard drive and made the swap space larger and then it worked.
so take a look at your partiotions -> df -k