I recently added a 5th site to westernpulp.com, where I have been running MSM successfully with 4 sites for months. I moved nothing, but duplicated some channels and templates. After I clicked the button to create the new site the screen went blank. I went to another browser (Safari) to check if the last site had been added. The new site was available on the menu, but when I tried to click on it, I was logged out. Back in my primary browser (Chrome), the process repeated. After opening up another tab (the original was still blank) and bringing up the CP, I tried to access my new site. I was immediately logged out in Chrome too.
My password no longer worked when trying to log in, so I clicked the “Forgot your password?” link and tried to login with my new password. That didn’t work either.
I see that Thomas Sausen has the same problem. I created a new thread because my update to the latest builds of EE and MSM went flawlessly on Friday, 10-22 and he referenced some other problems that I didn’t experience.