Hello @wei503,

    Last night I left a file open and running on Autocad, then minimized it.  I arrived at my computer this morning and had no issue opening up the minimized running file.  So, step one was to see if that caused an issue, which it did not.  Tonight I will close all drawings but keep Autocad running, then minimize it and walk away for the evening.  I'll report back tomorrow.  Next time it hangs up I will follow your instruction and get you the requested file.

Many thanks,

Brandon