Safari problems after update to 3.5.2

Recently updated site to latest WordPress and all plugins. Now the website cant be accessed by the company owners.. two different macs running safari? They can view it in Chrome and on iPhone but not in Safari?

I can access it in every browser including Safari and iphone/ipad etc but they cant.. just says safari cant load the page…she emptied the cache, and it loaded some backround images of the menu bar… then failed to open?

Site is https://www.radioactivepromotions.co.uk/

Any help would be great?