I have document created in Word. Word started not to save anything (this is on System 7) with a large error message that needs a complex change in something or other. Not wanting to buy a new version of Office, I down loaded Libre. It worked just fine saving in MS Word or ODT. However, it just started to generate the MS word error if I tried to save in Word format. If I try to save in ODT, the program freezes and I see Word is also launched.
It is very unusual. Something is very strange on your system (what is “System 7” by the way? did you mean Windows 7? Or do you use a non-Windows OS which is also supported by MS Office, like macOS…?)
It could be something like virus maybe. Anyway, given that your MS Office started to refuse working previously, it’s something really weird, and both problems (with MS Office, and now with LibreOffice) indicate not that you need to buy a program, but reinstall your OS.
Which distro are you using ?