I would say it depends on how long it's been happening and whether you're getting any other errors. I believe what happens when you get the 'already logged in' error is that your character I'm the game is still loaded even though the game is closed, so it sometimes takes a while for you to actually 'log out'. It tends to clear itself up relatively quickly though, from my experience, within 5 or so minutes. There are times when it's being super stubborn and might take 10 or longer, but those are rare instances.
I would say I doubt it's hacking since even if someone did know your login info they likely couldn't log in on another computer while the account is already logged in (because it's already in use), but I don't actually know if being logged in prevents you from logging in on another computer, or if it would boot you on the first computer and log you in on the second.
PC-NA | Been around since closed beta
Avid RPer. Hit me up in-game @Ras_Lei if you're interested in getting together for some arr-pee shenanigans!
RP Characters:
Sarah Lacroix: Breton Vampire who really really REALLY likes likes learning Magick and also her Altmer husbando
Kaalhil Swiftstrike: Tiny shapeshifting monster hunter Bosmeri lady with enough sass to kill a dragon or ten
Gwendolyn Jenelle: Friendly healer with a coffee addiction and her own medical practice
Krisiel: Literally crazy Werewolf, no like legit insane. She nuts
Kiju Veran: Ex-Fighters Guild Suthay who likes to punch things and is also a spy and ALSO a Werewolf
Niralae Elsinal: Young Altmeri woman with way too much Magicka and Vampire husbando
Slondor: TESified Slenderman, except lazier and has more of a thing for deals than Clavicus Vile does
Marius Vastino: Sarah's Imperial apathetic sire who likes to monologue
Lirawyn Calatare: Traveling performer and bard who's 101% vanilla bean
Soliril Larethian: Blind alchemist who uses animals to see and brews plagues in his spare time
This was actually mentioned in the patch notes, idk if it was Harrowstorm or Dragonhold or maybe a tiny bit earlier. It’s intentional to get the message in order to prevent you from accessing the server too quickly. A lot of times this is frustrating because it extends the time until you can get back into the game when you crash in a raid.
As the server gets more unstable, they put in more bandaid fixes.