ethernet connections in Karmic - how do I tame network manager?

[Lisi]

Can I just uninstall Network Manager (Network Mangler???) and create 
an /etc/network/interfaces file?

It isn't that it isn't connecting at all, it not connecting properly.

Ping works - by IP and by URL.  (Once I have persuaded network manager to 
start the connection. :-(  )

IP address in browser works (after a fashion) for some sites but not for 
others.

URL in browser is completely non-functional.

LinuxMint on this exact set-up was a disaster - but at least it connected 
properly by DHCP.

All help most gratefully received!!  (Honestly, Myriam - I really am 
grateful - just very pushed for time on this particular job.)
Lisi