Adobe Acrobat Pro DC Freezing/Crashing Problems

I have several PDF documents that I create daily. These files are formatted and edited each day using various Acrobat tools. I am having multiple problems on a daily basis with my Acrobat program. These include the following:

• The program freezes up as I am working in a specific PDF. Sometimes this will generate an error message stating that the program has stopped working and to check for errors. Most days, I do have a portfolio in which there are multiple PDFs. Even on the days there is only a single PDF, I still have the same issues. 
• When I create the PDF and begin making changes, I will try to save the changes, and when I try to save, I receive an error message that other users are in the file. Therefore, I cannot save the changes even though no other users are in the file.

These problems are impairing my ability to save these files and work in them in a timely manner. We have only had the product for a month now, but we have been experiencing these issues from the start. If we cannot resolve these issues, then we cannot use the software for our intended purpose.