Cannot connect new Vaio Vista with usb modem

[#1]

I've just aquired a new Vaio laptop running Vista and cannot connect to my Metronet service.
I'm using a new Zoom 5510 usb modem which was labelled as 'Works with Vista', and I downloaded a Vista driver for it.  Having installed it everything reports as working correctly - the power light is on, the link light is on solidly, and I have gone through all the procedures for setting up the account.
However when I try to connect I get an 'Error 815' report - 'The broadband network connection could not be established on your computer because the remote server is not responding'
I am using the same phone cable to connect the laptop which I am now using to send this question, switching it between my desktop and the new laptop, so all filters are working properly and the line is OK.
Any ideas I might try to resolve this?

[#2]

You might find the third (final) post in this MS Technet topic helpful.
It seems another WAN connection might have set itself up in Network Connections configured as 'default'; it's worth checking if that applies in your case.

[#3]

No, my Metronet connection is the default in Network Connections, and there is no other broadband connection there.

[#4]

A common problem is inadvertently leaving off the realm (after the '@') when inputting the broadband username. Do you have this correct?
From orbrey's My Broadband Doesn’t Work! blog here

Quote

the broadband username for MetroNet should be: (rephrasing the text in the table) <username>@dsl2.net or <username>@metro1.net You should be able to use either realm, please test with both. Also please note that the first realm is dsl2.net (dee-ess-el-two dot net) and NOT ds12.net (dee-ess twelve dot net).

[#5]

No, I didn't leave off the realm or mis-spell it.
Any more suggestions?

[#6]

So you can connect with another computer using, I assume, a built in dialup modem? Have you tried using the Zoom modem on this PC? That might narrow down the problem, especially if it runs XP or something other than Vista. If the modem works on the desktop then it has to be either incorrect login settings, or maybe the wrong driver,or maybe a faulty USB port. If it doesn't work it suggests a faulty modem. If the modem is faulty then replace it with a router. These plug in to the network port rather than USB, and don't rely on drivers.

[#7]

Thank you for your help.  In checking out the modem, I discovered that because Vista blocks unknown startup programs, and I plugged my modem into the computer before manually restarting these programs, the connection setup utility (one of the blocked programs) could not do its job.
Simply leaving the modem unplugged from the USB port until AFTER I started this program solved the problem.
Apparently, the crucial point about most modems and Vista is that the US standard of PPPoE is installed by default and the UK PPPoA standard has to be manually configured.

[#8]

Do you have an American computer?

[#9]

No, it's a UK model but as with most things, the whole world revolves around the US!