I think i have a similar problem now. I did a fresh install with X-Cart Gold 3.4.1 but when finished i've got the following error:
Can't write template cache in the directory: //templates_c.
Please check if it exists, and have writable permissions.
So I checked permissions and they are set to 777 so this should be right. Group and owner are
www.users instead of nobody.nobody. This is created by X-Cart self. What am I doing wrong here ?