30s for ping to start / NDIS filterq

When pinging a dns name like www.google.com or even localhost ping does not start for 30 seconds.

pinging ip addresses is fine.

When I disabled the NDIS filter on my network connection the problem went away.

Am I now not running a firewall? why does avast cause such a devastating detrimental effect on my network connections.

What is the problem? and how is it fixed ?

Please do not simply tell me to re install, I really need to know why this is a problem in the first place or I may as well simply install a different security suite.

Thanks in advance for any help.