How can I unblock ICMP?

[musiclover]

When trying to make a new tunnel I get the message:
Error: Your IPv4 endpoint is unreachable or unstable. Please make sure ICMP is not blocked.

This is even without Firewall. What can I do to make a tunnel?

[cholzhauer]

What OS are you running?  You're sure that you've either allowed ICMP through that firewall or turned off the firewall all together? 

Are you behind a NAT router?

Is there a firewall on your cable modem or DSL modem?

[musiclover]

I am using Windows Xp SP3. And I started windows without turning the firewall on. My adsl modem has no firewall. Maybe the problem lies with my provider (KPN)

[cholzhauer]

It is possible...do you know if they are blocking ICMP to end users?  You might want to ask them that...if they don't block it, at least you'll be able to rule something out.