Problems with wireless Internet connection

Hi everyone,

I had huge problems with my Mac the last days, so I decided to do a reinstall. It didn't help, but I found out later that I have a broken RAM module which was causing all the problems.

Now whenever I want to connect to the Internet with my Aiport Extreme Base station, I can't. It's just telling me it's searching for the PPPoE host (edit: or exchanging data with PPPoE), while I can connect via Ethernet just fine. I'm using the same login and password, which I double-checked.

What's also strange is that since the reinstall, I can't use WPA2 anymore. The option isn't included when I select the security method through Airport Admin Utility.

Any ideas?

Edit2: Hmm, now I also have problems with the Ethernet connection. It only works in 10% of all cases. But it still works sometimes. This is really frustrating. Although I begin to believe that the reinstall caused all this to happen. But I'm not sure if another one would help...

Last Edit: Going back to the standard firmware (5.5.1) through Airport Admin Utility solved the problem about the Internet connection. I still can't use WPA2, but this isn't such a big problem yet.