What does it mean when the folder name and filenames turn green in a window?


I don't do any work on the network, but I had the guys set up a folder on the LAN server that all pcs could access. After I copied and pasted files a few times from one pc to another, it stopped allowing me:

Access denied, make sure it is not write-protected or in use....

I know it isn't because I copied before, and i was the only one using it. Also, the folder is full access to all users.

Why did the name under the folder and all files turn green??
Why can't I copy the files anymore?

Thanks
Wengang