RE: Any other files on my desktop computer that end in .tax2019 or .tax?
*.tax2019 -- Just one TTax file on my computer @ ~13.3MB (my preliminary tax file for 2019). Note: I have never used the TTax desktop software to enter Form 1099-MISC data for non-employee contractors. This year, for the first time, I opted to upgrade my TTax desktop software (from Premier to Home & Business) in order to try out the online Quick Employee Forms offered by Intuit/TTax.
*.tax -- Just some archived TTax files from 2007 and before.