HTTP Error 407: Proxy Authentication Required

Hi,

I am new to Calibre and find it to be amazing.

When trying to download news or metadata I get the following error:

HTTP Error 407: Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. )

This only happens at work when connected to the LAN. At home I connect via Wi-Fi and it works perfectly.

I am running Windows XP and Calibre Portable.

Is this a Company Firewall issue?

Thanks!!!!!!