PS C:\Users\toiletduk> Get-ProcessLife mirc
mirc (42104): 2 hours 13 minutes 27 seconds
mirc (42272): 1 day 4 hours 11 minutes 6 seconds
PID 42104 is the 7.76 beta you gave me, and 42272 is my normally installed 7.77 (with WinDbg attached). The last crash of 7.77 was around 7 hours in (subtracted the current runtime from my system uptime, and I noticed it was dead within a minute or two), so I'll keep pushing.
As far as my antivirus stuff, I use the Windows Defender junk, but I haven't changed any settings. The only thing really changed recently was updating to 24H2 (it's final, just a limited rollout), but that was a whole week to the day before the first crash, so I ruled that out.
