Remote assistance DNS name resolution problem

[Mark v1.966]

Last night I was helping a relative, (with no IT knowledge), using Remote Assistance for only the second time. I right-clicked on 'Help and Support' in her taskbar and mistakenly closed it, as it was actually the RA application itself it seems, although she said she'd accessed it via 'Accessories' rather than 'Help and Support Centre'. I suppose it must show the same thing in the taskbar. Anyway, that ended the session, but I was unable to reconnect, getting the error message:- 'Could not connect to remote computer because DNS name could not be resolved'. Using dynamic IPs can cause this reconnection problem, but even when fresh email invites were sent, the same error messages popped up. I've tried getting her to send Live Messenger invites too, but with no luck. For some reason we can't get Messenger to transmit voice or video either. She's only just set it up, so I don't know if that problem is independent, or not. (There have been some issues on the Microsoft server side recently). Skype seems OK, if a little slow. I'd installed XP SP3 just prior to this on her PC, and at first the NIS protection showed that email/messenger protection was disabled, and it couldn't be re-enabled until after a reboot. She's able to access the internet OK, although bandwith tests show big fluctuations on download, 6.5-2.9Mb/s and only around 0.3Mb/s upload). Because she's never tested her bandwith before I don't know what her normal upload should be with an ordinary ADSL connection, but given her proximity to the exchange and the 6.5Mb/s on an 'Up to 8Mb/s' service, it seems suspiciously low. The remote access on both occasions was slow too, with about 0.5-3 second delay, although I don't know what the normal behaviour of it is like, and whether this is just the price of having to use Remote Assistance instead of Remote Desktop. We were using Skype during the session, so perhaps that was affecting it too, being a P2P network, although, if their publicity is to be believed, even supernodes shouldn't be that badly affected. One possibility is that her BT Hub, (a notoriously useless piece of equipment) is being leeched, as hubs divide bandwith with other users. Of course, I can't currently access it remotely to switch off the wireless and/or check whether it's even got the WEP default enabled, let alone WPA, and that's beyond her. Unfortunately, she doesn't have a spare computer with XP to help diagnose where the problem is either. All my own settings remain the same, and I've tried getting her to change from Norton to Windows firewall, and even switch both off temporarily, so this obviously isn't the problem. (After updating to Kaspersky 7 on my own PC some time ago I found XP SP3 had switched on Windows firewall, despite it supposedly detecting third party apps and switching off automatically). Any suggestions as to probable cause and remedy? P.S. I've just tried flushing my DNS cache, but I'll have to wait until tomorrow now to find out if that will do the trick.

[smoggy]

this site seems to suggest it is a router ip addressing problem
_http://www.techspot.com/vb/all/windows/t-59410-Can-anyone-tell-me-what-Im-doing-wrong-for-remote-assistance.html

now I know nothing about BT hubs but is it possible to connect broadband directly to the computer bypassing the hub. (still don't know if that would cure the problem)

[Mark v1.966]

Been there, read that, but thanks for the suggestion. I'll see what happens now I've flushed my DNS cache. Thinking about it, I'm hopeful that the accidental crash left a bad DNS entry which will have been cleared. We didn't have any problems before then.

[Mark v1.966]

Just tried RA again, and it's now working, having cleared the DNS cache. For anyone reading this post because they have encountered a similar problem, but is unsure how to do this, in XP this is done via:-

Start > Run > type cmd > OK > in the command prompt window, type ipconfig/flushdns > Enter

[Mark v1.966]

I discovered the failure to transmit voice/video with Windows Live Messenger was due to UPnP not being enabled on the BT Home Hub to allow NAT traversal. I don't like having to use UPnP, as it contains various security vulnerabilities, but Skype doesn't have an AV program interface, as well as using P2P, so it's a matter of which you consider to be the lesser of the two evils.