I'm not sure if this is a 'Forum' problem or not.

I've recently started to use a Windows 8 'phone to browse the Forums when out and about. Whenever I try to reply to a Post using this device, the on screen keyboard pops up and then immediately pops down before I have a chance to enter anything. It doesn't happen on any other sites / Forums I visit. It makes no difference if I use 'Quick Reply' or 'Go Advanced' and it doesn't happen when I enter my Username and Password to log on - that all goes smoothly.

Any ideas?