Updater closing upon entering // account-related

Hello.

since today my sister and I have met a rather odd problem with the game client, which seemed to be related to her computer/her client at first, but upon further investigation is actually related to her user account data.

she updated her account with her game code today, the mogstation already shows her having the 30 days added.

when she logs into the game client a windows error message pops up that says the program caused an error (the typical message where they ask you to send a report or to look for online solutions)

after reinstalling the client and a rather odd message about her connection changing (definitely not), the same problem still arose.

being a little fed-up and in the mood to test random things I tried logging into MY account on HER computer - and surprisingly it went through. I was able to log into my account and play normally.

we then proceeded to try and have her log in on my computer - and funny, we get the same windows error again and the client automatically shuts down.

edit: totally forgot to mention. yes, we did change her password as the e-mail she got asked her to.