Two admins are seeing "This website has a redirect loop"

Hi,

We are three admins on the site, and the two others beside me (Kasper Snæver Andersen) are experiencing some weird problems. When they are clicking on the buy link to two of the memberships (this is one of them http://odds24.dk/registrering/?membership_id=593), they are getting the message from the browser that says the website has a redirect loop. When I try and when they try from other accounts everything works perfect, but with these two admin accounts it's different.

Update: We have made a new account for one of the admins (Jesper) and the problem with the redirect loop is fixed for him. But we still need the last admin.

We also have another fatal problem. The pricing are different, when I select the membership called "1. Halvsæson" it's saying that the price is DKK 1599 on the page with a Pay button (and Stripe is also showing this price), but the price we have set in admin is 1349 (which should be showing instead of 1599).