Guys... if a problem like this is happening it's due to a script conflict most likely and with a user on a lame browser like IE that falls over dead with any script errors. Items to check:
- always make sure you are using the latest version of DT Register. The last package did include some script changes for the purpose of trying to reduce the chances of conflicts with other plugins and templates.
- check your event fees. You should have an individual rate and at least one group rate. Even if you don't use groups, you'll see a group rate set as $0 for a group of 0. This is NOT a problem. It's there so you have a group rate to edit and use if needed. Make sure you don't have any group rate entries for member number of "1". That will get goofy. Also make sure you don't have a bunch of extra group of "0" entries showing here as duplicates. That's been seen occasionally on sites after migrating from 2.6 to 2.7. Delete the extras.
- disable any site cache (joomla, plugins, template) as they MAY be causing a snag somewhere. Some cache plugins are pretty hard-core and cause more harm than good.
- check your browser for any script errors. IE will show them in a very irritating manner usually so they're easy to see there. In Firefox, use Firebug. These will help you track down the source of any issues. Note that just because a script error pops up on a DT Register page doesn't mean that it is being CAUSED by DT Register. For example, I just checked evie's site and found the source of the script errors on their site was a custom module containing code to follow them on Facebook, Twitter, etc. Disabling that made the errors go away.
It just takes something small somewhere in your site to throw a wrench in things. If you have this problem and can't sort it out, submit a ticket.