I'm not sure if this is only happening locally (I would think no, but I would also think it'd have been reported by now if not), but I'm having trouble getting to pages on SE sites. I get the Oops page, and the embedded error message is:
Hashtable insert failed. Load factor too high. The most common cause is multiple threads writing to the Hashtable simultaneously.
It's happened on UL, WA, and Android, both asking a question and just trying to open existing questions. I went back and tried the trilogy; SO and MSO are both fine, but SU and SF have the same problem