dial-up error 720 and network adapter issues

When I try to connect to my dial-up connection, just after it says "Registering your computer on the network" I get
error 720: a connection to the remote computer could not be established.

I have contacted my isp, and the issue apprears to be on my end, not theirs

Additionally in my network adapters: you can see the yellow-marked adapters in this screenshot
http://i1178.photobucket.com/albums/x374/K29000/network_adapters.jpg
have errors:
Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)

I am not sure if that is related to my dial-up problem. They all seem to be duplicates of network adapters that are working fine. (Except they say "eacfilt miniport" at the end)
I have tried uninstalling these duplicates which I think are leftovers from some other software that I may have had installed at some point(It says the vendor is Nortel but I no longer have any Nortel software on this machine), but they will not remove.

I can still connect to the internet fine via a usb 3G modem that I have borrowed. Although, when I do it gives me a message that "another computer on the network has the same IP address as this one" but after closing the message, the internet still works fine.
I have been unable to check whether the ethernet and wifi works correctly. The last time I used them was about a year ago.
I'm on Vista Business 32 bit SP3. Laptop: Acer Travelmate 5320
Any help would be greatly appreciated.

Run msconfig.exe and look for anything Nortel in the Services and Startup tabs. It may not be uninstalled.

Nortel is vpn software.
go into Network and sharing center and click on manage network connections.
right click on local area connection and choose properties
See if any vpn protocols are listed, if they are click on them and remove.

Thanks for the replies.

I did not find anything using msconfig.exe. I do recall unsinstalling an old VPN client a month or so ago. I have checked if I can restore to that point, but its too long ago.

When I right click the Local Area Connection the drivers listed are:
Client For Microsoft Networks
Eacfilt Driver
QoS PacketScheduler
Internet Protocol Version 6
Internet Protocol Version 4
Link Layer Topplogy Discovery Mapper I/O Driver
Link Layer Topology Discovery Responder

So Eacfilt driver appears to be the only one that needs to go. When I try to uninstall it I get:
ERROR:"Could not uninstall the Eacfilt Driver feature. Eacfilt Driver is still required by the following feature(s) and cannot be unistalled until those features are unisntalled: Filter Driver"

What should I do now?

In your local area connectin it shows, Eacfilt driver, remove it.

When I try I get an error dialog:
"Could not uninstall the Eacfilt Driver feature. Eacfilt Driver is still required by the following feature(s) and cannot be unistalled until those features are unisntalled: Filter Driver"

Have you tried in safe mode?

I can't access the Network and Sharing centre from safe mode. Its not in the control panel and if I try Start Menu->Connect->Open Network and Sharing Center, nothing happens.

Also I get the same error as before from Safe Mode with Networking

I was just thinking. Since device manager is hiding the non-eacfilt versions of the drivers, is there any way I can lower the priority of the eacfilt ones, so that they are not the ones being used, causing the standard microsoft ones to come into play? Will that help at all if it can be done? Not sure how it all works.

Did you do what I requested?

Yes there is definitely no service or startup item related to norton, vpn or eacfilt

I was looking around the web a little bit and found a couple of things that might give you some ideas. Two of them are not for Vista and none of the messages match the one you're getting-

Error 720: No PPP Control Protocols Configured

Dial Up error 720: Solution for Windows Vista Home Edition? - Microsoft Answers

PPTP VPN on Windows 7 - error 720

Someone at the microsoft support forums has managed to help me fix the errors in the networking adapters. The eacfilt ones are now gone. However, the dialup issue they have not resolved. All my netwotk adapters are now fine, but the dialup 720 error is still there. I've also noticed that under the Local Area Connection it still lists Eacfilt under the drivers its using, even though they're no longer in the device manager. I'll have a look at the links you posted. Thank you for your time.