We have a customer whose site is hosted by themselves within their own domain. They now have a requirement to allow 'external' users to edit in the site. The users log in via UNC to the domain, and can see the site OK. However, if they log in to EPiServer the functionality is 'broken' - for instance, an attempt to expand items in the tree by clicking the '+' gives a Javascript error: 'Invalid Argument' at Line 140. Debugging shows this is line 140 of system.js: source.insertAdjacentElement('beforeBegin',target);. There are many other instances of this 'broken' behaviour - searching for users returns no results, and creating a new page and pressing 'Save and Publish' simply returns an empty editor page without publishing. I suspect that this may be due to permissions for the UNC user in IIS - has anyone else come up against something similar? TIA /Mark