The file picker on our Moodle site hangs on the progress bar - this happens in Chrome, IE9, and Firefox when logged in as the site admin. It wasn't working on version 2.1 and upgrading to 2.2 (build 20120119) hasn't solved it. Chrome reports "not loaded: form_filemanager" or "not loaded: form_filepicker" depending on the block.
I've seen the same sort of problem posted (http://moodle.org/mod/forum/discuss.php?d=175696, http://moodle.org/mod/forum/discuss.php?d=193368, http://moodle.org/mod/forum/discuss.php?d=175153, http://moodle.org/mod/forum/discuss.php?d=189540) without any obvious way of resolving the issue.
I guess there's some sort of permission problem - if anyone could point a likely direction in which to start looking it'd be much appreciated.
I have been getting the same problems with the file upload. Some computers can upload and some can't. There seems like there is no logic behind the problem other then we are seeing the same problems in chrome as you are getting. And I there is also illegal JSON error in Opera 11.
I can't seem be able to figure out what is the problem it is hard to pinpoint it, since it seems to be working sometimes in some computers and sometimes some roles like i.e. teacher isn't able to upload into the course he is supposed to be the teacher in.
I am running moodle 2.2.1+ the newest from GIT
If it helps, our problem was caused by a block containing a Constant Contact questionnaire creating some sort of script conflict so I'd look for something similar - not quite sure what would make it affect some client computers but not others though.