Don't think it's your phone problem unless you can't connect to other WiFi as well.
Previously I reply to you already, after type ifconfig, check your IP Address under wlan0 is it the same as your PC obtained address (only the last part should be different).
Just to make sure you're connecting properly and not in ad-hoc mode.
Secondly, can you use command prompt in your PC Windows and type "ipconfig /all" and print the screen capture, so I can check the IP and DNS settings.
From there, you can manually set your N900 connection to your router similar to your PC, only change the last part of the IP address.
Example: 192.168.1.X
This is manual connection settings and should work better than automatic.
Means now it's working?
Probably the media daemon crash or something previously.
now i load the original profile (600mhz) & the media player work fine.. maybe got conflict with media player kernel..