Did you pinpoint exactly which extension was causing it? Since it's much less frequent without it, you might be able to figure out what the problem is based off what the extension does.
Unfortunately not. I was hoping that Chrome wouldn't crash with no extensions installed and that after a week of no crashing I could begin to install them again and see what would cause it to start crashing again, but it's crashed a few times today already with no extensions installed. It crashed once and then Chrome refused to open again until I rebooted my PC. I have now signed out of Chrome as suggested by Travis - wonder if that will make any difference. Next thing to try is what Okedokey suggested.
It seems to crash when opening new tabs or closing tabs when at least 4 or 5 are already open.
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Edit: I signed out of Chrome and then it just crashed again with only three tabs open! So that didn't sort it. I've now renamed the Chrome executable to chrome.exe and created a shortcut to that on my desktop (as instructed by
@Okedokey) which appears to have reset Chrome. Let's see if that makes any difference.