Category Error

I hope this is a silly question and I hope someone can help me
I have just installed option theme to WordPress with the demo data
before I start setting up everything on the template I noticed when I click on one of the demo products or click on any one of the categories it seems to go to a dead Page it says something like “oops that was embarrassing was” hope someone out there has had the same problem and fix that and could help me please see the picture of the problem thanks guys.