The UserOptions for a user to set up the default opportunity products was serialized to XML in a different format in version 6.2 than it is in version 7.5. If you try to insert an opportunity or go to the Options…Opportunity….Products for a user that has settings saved in version 6.2 then the SalesLogix Web client locks up. You have one of two options:
1. Remove the UserOption rows for all users dealing with Opportunity Product Defaults.
2. Go into the LAN client as the user and make a change to the opportunity poruct defaults for products there in the 7.5 lan client. This will serialize the XML in a format that the 7.5 web client can use.