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Please let us know the Illustrator version you are using-i.e. latest or earlier version. Second please let us know if you are PC or Mac and what system as this can give us clues as to what might be happeniing.
How many characters in the whole file path? Try moving it to the desktop and open from there.
Sorry to hear about your experience. Would you mind sharing version of the OS & Illustrator? Are you trying to save file on a network location?
This information would help us assist you accordingly.
Additionally, please try suggestions given on this community post(https://community.adobe.com/t5/illustrator/resolve-slow-performance-and-unexpected-behaviors-in-illu...) & let us know if it helps.