I find when using Hotspots for wireless connections when I am out travelling I often receive the blue screen on my Dell Inspiron 6400 laptop. It has vista installed
I never get the screen on the wireless network at home.

Does this mean I need to reinstall vista?

More likely a driver issue. Go to Dell.com and look for an updated driver for your wireless card.
http://support.dell.com/support/downloads/driverslist.aspx?os=WLH&osl=EN&catid=-1&impid=-1&servicetag=&SystemID=INSPIRONI6400%2FE1505&hidos =WW1&hidlang=en
There is an Intel Pro Wireless updated just last week.