Hi! I have a similar problem with prestashop 1.6.0.6 and themes. Products with combinations dont work. The Prices are reset to 0. but when viewed in product-page. in cart prices are ok again. the real price shows up for a second - and then its back to 0.
i checked the overrides folder - and there are a couple of php files. one is calles "product" - when i disable the php in this file, the product-page in frontend turns white and empty ... so, i am not very experienced in php ... but you think the problem is this file?