Automatic Logout On Skybet

[Quoi]

Having a bit of trouble using my skybet account because it keeps logging me out after a couple of minutes even while I am using it. Skybet site says auto logout occurs if not used for 90 mins.
Any idea what might cause this? - it was fine a couple of weeks ago last time I used it.
I use the latest firefox and the skybet help desk told me to switch to chrome even though firefox is approved by them.
Just one extra bit of info, I closed firefox while logged in to skybet and then 2 hours later went back in to find I was still logged in to skybet.
Skybet are basically telling me to clear cookies & history (done) & then turn my machine off and on again - clueless.