Error message in opening or cleaning a TagEditor file:
Failed to retrieve tag toolbar settings for plugin file format error

Possible Solution:
Open TagEditor with Jedit or note pad. Replace "InDesign Filter" for "Indesign Filter" (depending on the Trados version, the D might change from capitalized to lower case) or viceversa. If you change it when you opening the file, you have to make sure that you change it back before submitting the file or your client/PM won't be able to clean it.