Say you want plugins for many datatypes on Linux... (it is possible this bug is generic, but I can reproduce it on linux...). You go download plugger (http://fredrik.hubbe.net/plugger). You then configure the helper apps you want to use as plugins. Then you change your mind. Squirrelled away in the .mozilla/appreg file is stale information that the plugin supports the previous data types. So you try to delete a mimetype in plugger, but nothing happens (as shown by the help->plugins list) in mozilla. Why doesn't mozilla just believe its plugins, rather than storing this copy of the data that can get out of sync? It took me hours to figure out what was happening, along with the hint of this bug documented in the plugger(7) man page for Netscape, so this one has been around a *LONG* time. Ugh... The "fix" is to remove your appreg file!

resolving as dup of bug 109739. the problem is that appreg increments forever - nothing ever gets deleted there. *** This bug has been marked as a duplicate of 109739 ***

mass duplicate verifications . For filtering purposes, pls use keywd "massdupverification"