this how to may help,

Modify Remote Assistance Invitation
When trying to remote access a XP computer to offer a remote assistance, you may receive the "Remote Assistance connection could not be established because the remote host name could not be resolved". One way to fix this problem is modifying the invitation file ...

Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net 
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com 
 URGENT  I need a response to this before the end of Dec. 14th, 2005!

 I kept getting the following error message on my Win XP Home Ed. SP2 PC
 after accepting an invitation 3 times by Windows Messenger IM to provide
 remote assistance to another Win XP Home Ed. SP2 PC behind a hardware
 firewall 12/12/05:

 Remote Assistance connection could not be established because the remote
 host name could not be resolved. Please try again.

 The following instructions to resolve the issue (from the indicated website
 adr in the previous post below) do not say how to edit the invitation IP
 address.  What does this phrase mean, and how does one do it on a Win XP
 Home Ed. PC behind a hardware (router) firewall from which you are being
 invited to offer remote assistance?

 I searched on edit the invitation IP address within XP Help & Support &
 the articles it referenced either said they did not apply to XP Home Ed. or
 they were not germane. I am not a firewall or Internet connection expert by
 any means  could someone please tell me what my friend with the PC behind
 the hardware firewall has to do to permit me to be able to see whats on his
 screen?

 "Q: How to fix the error "Remote Assistance connection could not be
 established because the remote host name could not be resolved"?

 A: When you receive an invitation from an Internet user whose computer is
 behind a router or firewall, the IP sent to you is the private IP behind the
 router or firewall. So that you can't access the computer. To fix this issue,
 1) edit the invitation IP address. 2) Use Windows Messenger to establish the
 Remote Assistance session." From website "www.chicagotech.net/rdesktop.htm"

 Subject: Re: Remote assistance error message 10/9/2005 9:01 AM PST

 By:Robert L [MS-MVP]
 In:microsoft.public.windowsxp.work_remotely

 You may need to edit the invitation. check this page for the details,

 remote desktop How to fix the error "Remote Assistance connection could not
 be established because ... 2) Use Windows Messenger to establish the Remote
 Assistance session. ...
       www.chicagotech.net/rdesktop.htm  

 Bob Lin, MS-MVP, MCSE & CNE
 Networking, Internet, Routing, VPN Troubleshooting on
 http://www.ChicagoTech.net
 How to Setup Windows, Network, VPN & Remote Access on
 http://www.HowToNetworking.com
   "jess" <jess@discussions.microsoft.com> wrote in message
 news:9E5997AF-33E2-4698-B950-81F30F049984@microsoft.com...
   i have been trying to open a remote connection for about 4 hours now and
   everytime i try to connect to his computer i always get this error message
   "Remote assistance connection could not be established because the remote
   host name could no be resolved. please try again." can anyone tell me how
 to
   fix that?