Unable to connect to clients via Remote Assistance or Remote Desktop

As my subject line says, we are no more able to connect out client workstations via Remote Assistance or Remote Desktop. It was working fine until last week but don’t know what went wrong, suddenly it stopped connecting. The problem appears but critical because not just the client computers, I’m even not able to connect my test computer here at the same location as the server. Let me provide you some info about my server first:

Server 2003 SBS in our headquarters
- DNS and WINS all go through here

Cisco PIX 506E at headquarters, Cisco PIX 501 at remote office (192.168.1.1 at hq, 192.168.0.1 at remote)
- VPN Tunnel

I’ve enabled Remote Assistance under Remote Assistance Group Policy, also made proper changes for Defining Port Exemptions and Program Exemptions under Firewall group policy but still the problem remains. I don’t know what else should I do. So request you guys to please help me out.

Thanks in advance.

Yep, its indeed a critical problem. Anyways, just follow these steps and see if it works:

• First of all rerun CEICW. During this make sure your SBS have proper internet configuration. For more help on this, check the following KB http://support.microsoft.com/kb/825763/en-us
• Once done, disable the firewall on the problematic client, then test this issue.
• Please telnet 3389 port from SBS to problematic client. If it not works, please check your VPN configuration. May be there are some firewalls block the connection?
• Remote Assistance will use multiple TCP port.

Thank you very much for your help Winckle, but before I read your post, I managed to fix the problem by deleting the existing firewall group permission, and creating a new one. Everything is working fine now. I can access my computers via Remote Assistance or Remote Desktop both. However i dint found the exact cause of the problem in Firewall.