New Hard Drive and App Store Error (18)

Hi there,

I recently had a new hard drive installed in my Mac Mini which contained a new install on it.

I simply selected my language, region, keyboard, WiFi etc... and then selected the option to restore from a backup (Time Machine).

The whole process (including a big IOS update and associatedd bits and pieces) was 'Apple smooth' and my content was all where it should be, untill I wanted to use a few programs like iPhoto and Safari. I keep getting this error:

I also noticed that there was an iPhoto update available and thought this might help - but allas:

Can you please advise on how/if these matters are caused/related and what ste\ps I should take to correct them.

mahonjt