Coming to you guys for help, I'm at a loss on this one...

Prior to installing SP1 it was "Error 6: handle is invalid"
So I don't know if I'm making progress or not...

background:
Compaq C571NR Notebook
Modem: HDAUDIO Soft Data Fax Modem with SmartCP
Home Prem. 32bit w/ SP1
AV: Norton

Windows states its "Up to date"
Installed Optional Newer Modem drivers (no change in error)

Problem seemed to occur after installing cumulative security update for IE 7 (KB950759) which was installed before Optional Modem Driver. (not verified, just what the laptop owner says)

Tried using a restore point to prior date but has an "unexpected error" during the restore an fails to do anything. (great to know that's working properly)

Tried the steps included in MS Article ID: 810979 to no avail.

Ive also tried following RAS & NDISWAN component corruption fixes. No help either.

I've completely uninstalled Modem & all RAS adapters listed in Device Manager (including hidden devices) Rebooted and resetup with brand new dialup connection.

Bouncing around reading random forums it appears vista has trouble with Dialup connections for some reason. Either chronic 720 errors, or this error 6 handle invalid. Hoping we can get this figured out, its becoming very frustrating.

EDIT:
Just an FYI the Network connection works fine, connects right up to a DHCP router and access the internet without a hitch. Just seems like when the PC tries to finalize authentication on a dialup connection it fails and gives the error 720.

I kept going in circles with this one

Does your ISP by any chance have a different number to dial to?

Nope. One number, and it worked fine before. An no other major complaints so it doesn't seem to be an issue on the ISP side.