[Plugin: W3 Total Cache] "Browser Cache" feature broken

Today, I got some complaints from users, that were offered a file download instead of my website. One user was helpful enough to tell me, that he was served gzip encoded content without a ‘Content-Encoding: gzip’ header.

I tracked this to the ‘Browser Cache’ feature of this plugin.

Can you check if there is a bug, where not all the necessary headers are sent to the client?

This problem dos not seem to be present in all browsers on all OSs. For example, I could not reproduce it with Chrome or Firefox on Ubuntu, but it occurred with all browsers incl. IE on Windows and with Chrome on Mac. With ‘curl’ it was quite reproduceable.

Also, it does not occur for all URLs, for example ‘/wp/archives/1431/’ showed the problem, but ‘/wp/archives/1431/?123’ did not.

http://wordpress.org/extend/plugins/w3-total-cache/