Diễn đàn hỗ trợ Firefox

Where can I get Firefox 52.9.0? There was a list of old versions here but now I can't find it. I found https://download2.portableapps.com/portableapps/FirefoxPortableLegacy52/FirefoxPortableLegacy52_52.9.0_English.paf.exe I really did not want the portable version but avast considers it a threat so it may not be genuine.

I've got a persistent issue where Firefox immediately crashes when I open it initially.

Starting it again after this crash works totally fine, though if I close out and re-open a few times it will crash consistently (after every 3-5th-ish open).

It has been happening for the last year or so, and despite clean installs of the browser as well as other diagnostics it won't go away. It's incredibly annoying :(

Hoping the Firefox community can give me a hand and help solve this.

Cheers, Ciaran