404 error – permalinks?

Hi Guys

I have been developing a multisite for a while and have been creating lots of test users with lots of posts and had a bit of a problem yesterday. All users when clicking on a post (to go to the second page – /blog/2014/01/16/post1/ ) I got a 404 error, this was for all users. When I created new users and done new posts and clicked on them, they didn’t get 404 errors, it was just for all other the users.

This was happening regardless of me changing the theme.

I was looking up the forums about this but couldn’t understand why it was happening to me until I worked out an odd fix – when I clicked on settings – permalinks on each user, the posts started to work again. I didn’t click save or made any changes when on permalinks either. Does anyone know why this was as this would help me if this happens again, otherwise when I have a live site I would have to tell all my users to just click settings-permalinks.

I have about 10 plugins running, I think maybe that could have caused the problem.