Internet connections vanished!!! HELP

[yerf]

I reinstalled XPPro because of a shutdown problem and now my internet connections have gone!
Not only have they gone but I can't reinstall them!
The 'Connect to' selection normally listed on the start menu has gone. When I open network connections and click on 'create a new connection' I then get the connection wizard and choose 'internet connection' but the next screen has the usual options greyed out and only offers broadband which I don't have.
If I use the Network troubleshooter and choose 'modem troubleshooter' and select 'I have problems connecting my modem to the internet' the dreaded blue screen crashes in with a memory dump and reboot.
If I go through Control Panel and look at modems my modem (external ISDN) checks out fine and is apparently working properly. Everything else on the computer seems to work fine including network connection to the one other computer I am using now (internal anologue modem).
I tried reinstalling XPPro but the same thing happens.
HELP!

[nomaxim]

Please don't double post.

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