Connection problems with Voyager 210 router

[#1]

Hello,
I'm posting on behalf of my sister who is a new Plusnet customer, but currently can't connect to the web and we're at a loss to work out what the problem might be.
The situation is :
She has a new Dell laptop running Windows Vista and BT Voyager 210 router.
Last night at the first connection attempt everything seemed to be fine and she could surf the web no problem. Today, however after a reboot of everything she can't connect to either the web or the router.
The strange thing is that the connection itself seems to be fine. She is able to ping external addresses and IPCONFIG shows that the machine has been given the standard 192.168.1.2 IP address by the router. It is just any attempt to connect to anything via the web browser seems to be blocked.
I'm a stranger to Windows Vista so wondered if there was some firewall setting or something else that might be stopping the connection? 
Any help or suggestions would be appreciated!

[#2]

What is the default gateway set to? It should be the ip of the router.
What error does she get?
Can she run from a cmd box
ping 194.119.131.66
ping www.plus.net ; (if this doesnt work its a DNS problem)
tracert 194.119.131.66
Post any results.
If you do a ipconfig /all get the results and enter them into the network card manually reboot and see if it works then you must enter ip, subnet, default, gateway, and dns
Can she get email?
If it was xp I would say the winsock was knackered.
If all the above work it must be the browser or firewall thats the problem

[#3]

Thanks for the reply samuria - I'll post any results when I can get them.

[#4]

The problem you have is that your router isn't even connected to the internet yet, so i doubt you can ping plusnet. If it won't let you get to 192.168.1.1 through internet explorer you may be able to use telnet to set the equipment up, if it then shows as connected and internet explorer still won't let you on then it will be a security issue.
Hopefully someone on here can help with the vista side soon.
regards
Emma

[#5]

Quote from: Emma

The problem you have is that your router isn't even connected to the internet yet, so i doubt you can ping plusnet.

Thanks, but she can ping plusnet - I can't get any more details today as she is out of contact, but yesterday she was able to ping (for example) www.google.co.uk with no problem.
I'm fairly sure that it is an OS security problem, but sadly that means they'll be ringing Plusnet support for advice tomorrow 

[#6]

Thanks for the responses on this. It turned out to be completely down to the wonderful free McAfee firewall software supplied with the machine. Once I'd removed this and replaced it with a free version of Zonealarm everything worked fine. 
Slightly easier than the support advice received from Dell which was to reinstall the drivers for the router...  not that relevant when connecting through the network card I would have though