I created a task list with the system account. This task list is not visible to other accounts. What could be the reason for this ? The Urls are the same and the second account (Jürgen Stürmer) has admin rights as well but is no systemaccount. I thought maybe the list is checked out but it seems there is no way to check out a task list.
The site has to be in the trusted pool of you internet explorer. Also, Active x and JS permissions has to be enabled. (By Jürgen Stürmer])
Add your SharePoint site to trusted and try this as well PROBLEMS WITH INTERNET EXPLORER 10 (IE10) AND SHAREPOINT
Also, disable extra add-ons (if any)