VPN won't connect: prefixes domain name

I have been having trouble with VPN connections. After much debugging, I
find that it is prefixing a domain name, and trying to login as
MYDOMAIN\myname, instead of myname.

Acer 212T laptop computer, Windows Millennium (ME, WinME), now has
latest updates (Didn't originally), latest drivers. Connection to
Internet via built-in modem, works OK. Have uninstalled and reinstalled
modem, TCP/IP, VPN, etc. Machine normally networked to Netware (using
latest Novell Client 32) and also to Microsoft domain; during testing,
not connected to network. During testing, "login to NT network"
unticked, all VPN options, including specifically "login to network" and
others (encryption, etc.) tried both ticked and unticked.

The VPN itself is working OK (can log in from Win98, WinXP, Win2000).

On checking the logs on the ME machine, amongst the mess there are clear
references to MYDOMAIN\myname. On checking the log of the router which
runs the VPN, there are absolutely clear references to inability to
login due to wrong name, password, or domain.

Best wishes,
--
Michael Salem