I was receiving a "Server Error (OK)" when trying to look at any folder. The contents of the folder were not displayed. Mail could be sent, settings could be viewed, but no messages were displayed. This occurred after an upgrade of PHP, Apache and several other applications on my Ubuntu server.
Alec, the Roundcube developer extraordinaire, saw what appeared to be an issue with compression. We were able to determine that mod_deflate was the culprit. Commenting out "SetOutputFilter DEFLATE" in the .htaccess file solved the issue and now folders can be viewed. I'm working to track down where the exact issue with mod_deflate lies, but this appears to have solved the issue.
Thanks for everyone's help!
Chris
List info: http://lists.roundcube.net/users/ BT/9b404e9e