The key is to look at the template you are using and see if it is compatible with the version of zen cart you have loaded...
You need to use WinMerge to compare the file stucture of your template compare to your version of zen to see if the .php coding has changed and if so, You have to fix it..

I would contact the Template designer you paid good money for this sleek looking site to run flawless with Zen cart...