I'm more than happy to help solve the "JFolder::folder: Path is not a folder: /language" bug.
However, as noted earlier, I've problem replicating this on my system.
If anyone of you is keen to get this bug fixed, I can help. However, you have to allow me to
- telnet into your system (as I need to go direct to some of those sh404 files to trace down the bug)
- log on to your joomla site as administrator
I would be more comfortable if it's a development system as oppose to a live site - as I might need to echo some debugging statements during the process of debugging. Also, please do a backup of your joomla site, if possible, just in case.
If you're keen, drop me an email, and I should be able to debug it within a couple of hours.