Error Installing Rated 3 out of 5 stars

It will not install on Firefox 3.6. Here's the error message:

Firefox could not install the file at

https://addons.mozilla.org/en-US/firefox/downloads/file/77071/book_burro-0.73-fx.xpi?src=addondetail&confirmed

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

This review is for a previous version of the add-on (0.73).