Rated 4 out of 5 stars

Not working for me while Slim Add-on Manager is enabled on FF 6.0a1 x64 on W7x64. Otherwise working right.

This review is for a previous version of the add-on (1.0b1pre.1-signed.1-signed). 

The beta you were using was not compatible with Firefox 6. It would not run correctly under any circumstances. Try the new version available now for Firefox 5/6/7. It has been tested to work specifically with Slim Addons Manager.