query.cookie.js 'Page Not Found' 406.shtml error

I'm getting using jstools and collpsiblock.

I'm getting an error in watchdog:

Type: page not found
Location http://www.domainname.com/sites/all/modules/jstools/jquery.cookie.js?m
Referrer http://www.domainname.com/admin/reports/dblog
Message 406.shtml
Severity warning

It happens on pretty much everypage and only when collapsiblock is turned on (probably because it's the only module that calls jstools and jquery.cookie). When I go to view source in firefox and see the jquery.cookie.js file it doesn't load it (although it's present in the folder). When I enable 'javascript optimization' the problem goes away, but I need to disable it while I'm in development.

Any help would be appreciated.