Repeating 404 Not Found error

Hi!

I have a problem with repeating 404 Not Found -errors on my website. Every time I reset the permalink settings they work for a couple of hours after which the error occurs again if I use the post name permalink setting. The plain setting works all the time but I would very much like to have the pages’ names in the urls. I have checked the .htaccess file and there is no problem. Any ideas what to do?

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