My wireless laptop won't work at home after returning from the office.?

I seldom have to go into the office to work. But when I do, I bring my laptop and use a wireless connection provided by my employer. The problem I have is when I return home to use my wireless laptop (i.e., I can't connect to the internet and my laptop prompts me for a pword which I don't have anyway). It's like my employer's wireless connection screws up my laptop's wireless connection when I return home. What is causing this? How do I fix it?