At some point in the conversion soiree, my table names became all lowercase.
Unfortunately, that's how Windows works by default; which is a pain if you ever change over to a Linux host; as Linux hosts require everything be CaSe SeNsItIVe and the setting "lower_case_table_names" just says to use all lowercase.
When we migrate to v8 we've been discussing having all lowercase table and field names for compatibility with this option.
Additional forum settings fix: All users were imported as Moderators.
This is a known bug and requires db manipulation or manually fixing each user in the Control Panel.
This is why I suggest upgrading to 7.2 then to the latest; I'll need to look at what got changed in the importer by a previous developer to make it incompatible with 7.2.
To "fix" this you'll need to hop through a couple of hoops, but basically what is happening is your group #2 users are now in the current group #2 which is Global Moderators, then #3 moderators (all of your users), etc.