I need more than 2 cents of advice. Arctic freeze caused a head level issue for me. I run my dust collector religiously but the air compressor is not always around when I need it so I blow clean less than I should. The day I fixed that issue was a hard freeze and my 2 heaters could only get the shop up to 38 F. I wanted to test it and did.
My new instant x stall has yet to be diagnosed or resolved. But I don't want to hijack the thread.
If Mo's issues weren't resolved I was going to suggest that the z encoder could have been jerked loose after a freeze or rapid thaw. Also if you haven't asked much of the machine in 10 years, you definitely want to run the lube maintenance on all vertical rods and rails from outer mains to inner z's and check the head pressure and bearings. Even a micro vibration in a loose z assembly can wreak havoc on ribbons, cables, encoders, and even bits and cause persistent and inconsistent failures.