I don't know if this will help at all but I'll throw it in the mix. Ever since the latest update I was unable to log into the game, from any of my accounts, on my primary computer. My secondary computer no problems. I did all I could think of to find out the problem. I did complete file check of eq directory (which in the past usually fixed this kind of problem) but no fix. I then did a reimage of my windows os partition (different than my eq one) and no fix. I then reinstalled EQ to a brand new directory and this fixed it. All this time I was logged into EQ on my secondary computer with no problems at all.
I don't know what got thwacked in my old EQ directory but something did. I left it intact so I could play around with it later. )
The biggest bitch was trying to copy over user files and settings (which should have been easy but I guess I made it hard). ))
Sorry for your woes though.
toejam