Arrowchat chat bar caching itself

[Beany]

I had Arrowchat working perfectly on a Jooma 3.3.6 website running on PHP 5.3.14
I moved the website to a new server running PHP 5.5.
Now for some reason, Arrowchat seems to be caching the chat bar.
If I log in first using a PC, the chat bar shows on a mobile device without switching to the mobile tab.
If I log on first using a mobile device, the mobile tab show on the PC browser instead of the chat bar.

Anyone got any ideas of how to fix this?

Website details:
Joomla 3.3.6
PHP 5.5
Zend Server with Zend optimiser enabled
Apache 2.2 with Google pagespeed mod