I would start by clearing the cache for ObjectDock (which means deleting the ObjectDock Plus folder found in the "C:\Documents and Settings\USERNAME\Local Settings\Application Data\Stardock" folder).
I wrote a mini tutorial on clearing the cache here http://corkyo.wincustomize.com/Articles.aspx?AID=82461
The process would be:
1 - Save theme
2 - Unload ObjectDock
3 - Clear the cache
4 - Start ObjectDock (which will load with the program defaults).
5 - Use the ObjectDock configuration panel to load the saved theme.
I would suggest recreating the dock entry that opens IE7, to remove any possible link issues.
Note - there is no folder named "cache", just folders bearing the program names which contain the cache of user preference configuration files.
If this fails, I would have to assume that IE7 is conflicting in some way.