Windows Explorer Restarting

Hi,

Hope someone can help, I have a new Latitude D830 running Vista with Service
Pack 1 on it, I am trying to unzip a file which is about 150mb compressed,
every time I try and unzip it Windows Explorer keeps restarting and then the
zip just closes and I end up trying to do the same thing again, I have
scanned for virus's and malware and nothing on the machine which I doubted as
I have only recently turned it on, does anyone know why this would be
happening?

Thanks