SAFARI HANGING/FREEZING

Hi I have an iMac with Lion OSX and the lastest Safari. When starting Safari up it freezes and the page doesn't load, or it loads but then freezes. We have two other laptops, a Mac and PC that are connecting OK, so I presume it's something in the iMac Safari software/settings that's gone awry. Any ideas about the problem and how to fix it (I've already reset Safari)

Ravensheugh