Rated 4 out of 5 stars

"You can only remove it when you do this:
In Registry Editor:
- Go to
HKEY_LOCAL_MACHINE \ SOFTWARE \ Mozilla \ Firefox \ Extensions
- Delete value {20a82645-c095-46ed-80e3-08825760534b}
In Firefox:
- Go to about:config
- enter microsoftdotnet in Filter
- Right-click general.useragent.extra.microsoftdotnet
- select Reset.
- Restart Firefox."

NOTE: In later editions of Firefox it is only the above key that needs to be deleted, there is no corresponding entry in about:config. Restarting Firefox after deleting the key will no longer display this add-on in add-ons