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templates_c needs to be writable by XOOPS (so pages can be cached there). In some servers it can be 755, others has to be 777.
You can try 755, and if it works, then you're set. If you needed the 777, then you have to let the system rebuild the templates once in a while (so you don't get blank pages, or outdated content).
I had that problem with surpass about a year or more ago. Maybe they fixed it, because I hadn't had to let the templates rebuild for a long time (I used to get emails from users about blank pages).
That has been my experience...