Hi John,

Thanks for your reply!

Our network is Mac based, and I normally work from the network to get the files, edit and save them. My files are not big at all (650 KB), and my autocad lt 2015 is up-to-date. My operating system is: OS X EI Capitan Version 10.11.5

I have the same issue while working with sheet sets (project manager in acad for mac), too!