Hi!
Sorry for late answer, problem of connexion since one week...
So, the problem is that ARI is loading jQuery Library without testing if an other one is already loaded.
But, the plugin jQuery Easy, if installed, activated, and set to load jQuery 1.8 from the plugin should solve this issue!
If not (but really, should, as already tested!) you can disabled the loading of jQuery Library in advanced Option of the module calendar
(yes, i have think of this option in case of...)
Best Regards,
Lyr!C