Hmm, I think I can help you. I had the same problem for quite some time.
1. Open the aeria website, by default you should be opening the mobile version.
2. Load any one of the forum pages. Underneath you should see a button called "load full site". Click it.
3. Now that the full site has opened, please open the said to login your account. Preferably make a bookmark for this login page. That's what I did.
4. After logging in, go to the top of the page where you should see the link which guides you to the various forums. Click on any of the forums you want and open a topic.
5. Hit the "new reply" button to make a new reply. This should work.
This is what I do for my mobile. If you're wondering what mobile I use, its a nokia x3 02, operating system is symbian. Hope this post was helpful.