Out of Memory

I have a user that will open up scanned .pdf files about 3 to 5 pages long.  She will be working in another program and when she click's back on the .pdf files, it will give her the "Out of Memory" errory, she wasn't doing any conversion, printing, etc. to the file, just viewing it.

Running Windows 10 Professional

Adobe Acrobat Pro DC Version 2015.006.30033

New HP computer with 6gb's of memory