I was just planning to post
a similar the same problem.
I can't get my site to go 'offline' If I change the 'website online' by removing the checkmark, I can click 'save changes', but it just doesn't save and the website stays online. I can change any other configurationsetting and then it does save. But then if i change a setting in combination with the offline checkmark...it doesn't save again...
I tried it in FF and IE, I'm using pivotx 2.3.0. and cleared the cache just to be sure.