Ethernet Controller problem

Hello everyone,

I need some help please. Here are the details:

I'm running on Windows 2000, and the
Ethernet Card is a Sitecom PCI Fast 10/100 Ethernet Adapter LN-020.

Here's the problem:
About a month ago (maybe less) I installed an Ethernet Card to use broadband and set up a wireless connection with via a router with our laptops. And everything was fine and sweet.
Then one day I logged on and got a 'New hardware found' message and it appears my Ethernet Card somehow how got uninstalled or its driver vanished. I have no idea how this has happened.
I got the Ethernet Manufacturers CD and tried to install the drivers. Nothing happens. The CD autoruns, seems to install some things, asks the computer to be restarted, and when it does, it autoruns again but does nothing. It has a clock interface that goes round and round and circles that light up to show progress, before the restart, four circles are lit up, afterwards it remains at four, even if I leave the computer running for two hours.
I have tried to manualy get the drivers from the CD and place them in the Drivers folder and get them recognised that way but it doesn't happen.
When I go into Device Manager, I see Ethernet Controller with a yellow question mark in other devices. I right click to install drivers but windows doesn't find them on the CD. It says under Properties 'The Device cannot start (CODE 10)'.
I've tried the manufacturers website, but haven't had any luck either.

I tried to solve the problem myself but I've run out of options. I need your help. I could always buy another Ethernet Card, but since the current one is only a month old, I'd rather get your help in identifying the problem. It's a right pain. And I can't understand why the driver won't even load.

Thanks everyone! Look forward to your advise.