No network (and internet) access - with a a non-dsl modem !

Hi
I'm in the African bush without any local help but crocodiles for suicide in case I can't solve the issue with you…
Under Windows7 RC 7100 with a modem (Nokia N91, with pcsuite driver last version), the internet connection worked well at the beginning, and after a few days, without changing anything, now it always says "no network access", with the yellow triangle.

All troubleshootings have not detected any issue.
The modem is still connecting to the computer (Dell studio 17), IPs are appearing, but "no network access".
On another computer under xp, the internet access is working fine.
I have already:
- unticked the IPv6
- switched off the other network cards (ethernet and wireless) in order to avoid conflicts
- switched off the windows firewall
- rebooted
- tried public and office networks (home network impossible without IPv6)

Please help!
Thks in advance.

Hopefully you won't have to resort to the crocs

What happens if you remove the modem from device manager and let it get re-detected and set up again?

Did you try rolling back with system restore and see if that worked (to see if it was a setting change causing the problem)?