I'm totaly new to m0n0wall and I have a strange Problem.

I replaced a commercial DSL-Router against a m0n0wall-Mini-PC.
Everything worked fine with the installation and I did a basic 
configuration mainly for my 10.1.1.xxx net.
m0n0wall Web interface works.

I can only surf to very few URLS like
http://www.schlecker.de or http://www.map24.com.
These 2 work perfectly fine. As soon as I try other URLs, I get nothing.

It looks, as if the DNS is not working properly or if certains IPs get 
filtered. But I have just the defaults.

My E-Mail programme is strange too. I can check if new E-Mail is there.
That works. But when the mailprogram starts downloading the mails, it 
gets stuck and doesn't get anything.

Whe I put my commercial DSL-Router back in, everything works.
m0n0wall back in. Only the 2 URLs work.

Any idea what this might be?

Kind regards
   Giselher Nitz