While adding products php printed the following,
Notice: Undefined offset: 0 in C:\Program Files\VertrigoServ\www\includes\common_functions.php on line 555
What do i have to do to remove/ fix this?

Hello,
 
If problem persist please contact our support team with your site details so they can check and fix this issue.
 
Thanks,
ViArt Support Team

Same problems with my setup, too.

Hello,
 
Usually it happens if there are no active top categories.
To fix this problem you can remove categories blocks from your pages until you will not have some active categories.
Also the fix for this problem will be available in our next 2.9 release.
 
Thanks,
ViArt Support Team