Can't access my other computer anymore

Hello,

I'm on a macbook pro and I need to be able to access my Powerbook G4 over the network. The G4 is hooked up with a cable straight to the router and the Macbook is wireless. I'm need to share two harddrives that I've hooked up to the G4.

It worked just fine before but now I'm getting this error:
http://imgur.com/GTYtLGR

I can still use the screen sharing so I'm not really sure what's going on. I'm loggin in as admin.

Thanks for your help!
H

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Also, I decided to let the media computer (G4) always have the same IP. Like this: http://i.imgur.com/jlnyWLL.png

Another weird thing is that my computer doesn't connect to the network automatically after a restart. Maybe it has got something to do with the fact that I changed the security to WPA2-PSK? Also I have automatic channel selection...