I’ve seen some WordPress users complaining that after they post something, sometimes their browser gave them a blank page, or an error. Many blamed it on the plugins. I had the same problem, and deactivating or removing plugins didn’t help.
I found out the real problem: Update services (Options – Writing – Update Services)
Try to root out the problematic site; they are indeed just normal websites so some of them might be outdated or dead. Your pages timed out, that’s why.
I just removed the entire list, and maybe look for a reliable list later. Now, I am posting without any problems. See me smiling? 🙂