It wont even download Rated 1 out of 5 stars

I have been trying for days to install this but every time I get

"Firefox could not install the file at

https://addons.mozilla.org/en-US/firefox/downloads/latest/3336/addon-3336-latest.xpi

because: Invalid file hash (possible download corruption)
-261"

This review is for a previous version of the add-on (0.40).