I suspect a lot of your problems stem from using Opera Mini, which tries to speed up your Internet browsing by doing all the hard work on
their servers then just sending a picture of the result to your phone[sup]*[/sup]. The errors your are getting about POST relate to entering data in forms (e.g. posting a message, filling in a box, etc.), so I suspect something is getting lost in translation.
Alas, I don't access The Forum with any mobile devices, and I have never used a Blackberry in my life, so I can't really answer your questions beyond that, I'm afraid.
* That's a very simplified version of what really happens, but it will do for now!