Computers in the office started loading windows for 10-20 minutes

Wojciech_Bogacz 

I have run into this problem with a group policy that handles folder redirection. If the sync relationship broke, then it wants to sync all of the files again which will cause a delay on login. I have a few users with an extreme amount of data even take up to an hour. We run a majority of desktops, so it doesn't happen very often at all. I would imagine it would happen more often with laptops. Especially if those laptops are taken off-site. May also be those laptops just trying to re-establish a trust relationship. Like many others have stated, I would check your group policies. Maybe run the group policy PowerShell command to see if they are applying correctly or if they are getting errors.