itchy01ca01: Unfortunately, I need a little more info.
That's fine, you can ask whatever you want.
itchy01ca01: I don't know what the game is,
It's Guns of Icarus Online, but that isn't relevant. The issue is with Steam itself.
itchy01ca01: Are you trying to play on a LAN?
No, the game is a remote-server-only deal (like an MMO).
itchy01ca01: Same Steam accounts? Different steam accounts?
Already said we both have our own individual, unshared accounts and we both own the game on our accounts.
itchy01ca01: Are you banned from Steam for any issue?
No, neither of us are.
itchy01ca01: Is one of you on a console, another on PC? Are you trying to play on separate PCs? The same PC?
Both on the same PC.
itchy01ca01: I will say it again, I don't think it is the games issue.
I already know it isn't. The issue is
definitely with Steam and I confirmed it with Valve that it is with Steam.
itchy01ca01: I would like to know what you are trying to do and how.
0) Log into my account on the computer
1) Launch my steam installation
2) Log into my Steam account
3) Launch the game
3.9) Log into her account on the computer
4) Launch her steam installation
5) Log into her steam account
6) Launch the game.
EDIT: Added the logging in to our respective accounts on the computer.
We are stopped at #4. She can't launch Steam. It's not her Steam installation and I am 100% sure of this, because if you do 456 then 123, we are stopped at #1.. I can't launch my Steam installation but hers launches.