I would re-install the wireless driver - remove it totally and then re-install using the latest drivers. I would also check that the Wireless card will work in a machine that can currently connect to rule out a card issue.
Maybe worth even adding a static IP address. Are there lights on the network card? If not, there is a communication problem with the actual card and maybe the port you're plugging into.
If there is flashing lights and asynchronous, (Orange and green light i believe) at least it can connect. You should be able to use the Cisco wireless client to configure the profile.
If the lights are flashing synchronously (together) it means you are connected.
Let me know what the state of things are and i'll attempt to help further, but don't dismiss uninstalling the wireless card and drivers and re-installing them as this can sort out a wealth of problems and we need to rule it out of the equation.
regards
