Situation
This message may appear for a number of reasons. Possible causes include that the company file is locked, access privileges for the company file may be incorrect, or there may not be enough room on the computer where the company file is stored.
Solution
Check to see that you have given full (read/write) access to the folder where your company file is located; in other words, be sure you're allowed to make changes to the file within the location you selected for the company file.
If you have very little room on the hard disk where your company file is stored, remove some items from the computer. You may also want to consider increasing the size of the computer's hard disk, since your company file will probably continue to increase in size over time.
Check these additional possible solutions: