Today I logged into a character in Plaza 1 (Teh Fabricator). I went to the subway and as I zoned, I was kicked back to the login screen.
No error message.

I tried several times to login to the same character, but was kicked back to login without even reaching syncronising. Again no error message.

I logged a different char (Trogdor) and attempted to zone from I_05 to I_06. The same problem occurred. No error message.

A third character I logged (DJmule) was in an abandoned cellar and was killed by an aggressor, zoned to Plaza one without incident. Zoned to the Concentre and was killed by a guard, zoned to Plaza 1 again.

I then tried to log Teh Fabricator and logged in at the zone reset position in the Subway.

I then tried to log Trogdor and logged in at the reset position of I_06.