I recently moved my forum to a new server and URL and since then some users are experiencing a bug when they log in. Sometimes they will appear logged in as a different user, with no relation to them. Any action, such as going to the home page or clicking the private messages menu, will cause it to reload and appear logged in as the correct user. At first, I thought this could be related to the new server using a cache system, but we have un-cached everything but the problem persists, though it doesn't happen very ofter now. Please help.