SEP11 miraculously blocking inbound traffic

Hi everybody

This might be somewhat obvious to some, but I actually don't seem to find the reason. Searching the KB and community didn't come up with really helpful stuff.

So I am so keen to ask ...

Here's a description of the configuration:

I got two locations - External and Internal (Basel).
External has got a full policy set attached to, while Internal does not have a FW-policy. You can see this in the screenshot below:

The locations get determined by IP-address and DNS-lookups. Whereas a client with 10.1.X.X and successful lookup is located in the "Internal" network.
Well - I got internal clients blocking incoming traffic on ports 137, 139 and 445 - Which does not make any sense to me. Because:

1. The affected client(s) are located in the "Internal" network
2. There is no FW-policy attached to the "Internal" network
3. I am not aware that the IP-policy would block this kind of traffic

Below there's a screenshot of one blocking-event.

Now - *What* is actually causing this and *how* to get this fixed?

I am thankful for hints :)

Feel free to ask further questions.