“Microsoft Excel Cannot Open or Save Any More Documents”
When opening a file downloaded from the Internet, or received as an attachment in Outlook, Excel prompts “Microsoft Excel cannot open or save any more documents because there is not enough available memory or disk space. To make more memory available, close workbooks or programs you no longer need. To free disk space, delete files you no longer need from the disk you are saving to.”
This occurs because Excel is opening the file in Protected Mode, but the firewall is off. Protected Mode reduces the functionality in the file for safety.
Enable and start the Windows Firewall.
If Windows Firewall is damaged instead of merely off, the following may help: Firewall Service Missing, Error 0x6D9.