Problem with SEF (resolved)

[wotnots]

My problem appears to be related to SEF. I have successfully created categories, added products but something has changed. The "Click here to improve product's rank in search engines (SEO)" will not open but I cannot save a new product because I get an error message saying that I must make it SEF, at least in English. On the products already added, they display incorrectly in Back Office (See attached screenprint)
Thi happens whether I have SEF enabled or not.
I have an htaccees file.
Can anyone help, please?
Clive
Here is a URL to the site http://www.wotnots.eu

[wotnots]

Obviously nobody is interested in helping me or they don't know how to resolve this problem. Therefore I intend to delete Prestahop, never to be used agin. Mac' E-Commerce looks a much better open source solution.