I understand that you can boot under TOS in CT60 mode. RIght?
So you don't use NVDI ? It's mandatory.
Try to use NVDI 5.03, I don't know how older versions behave.
Your boot disk should look like this, nothing more :
Xboot.prg. Not necessary but useful to set up your boot. Use uniquely the patched version share in the forum.
NVDI.prg. Ensure that the running order is the same and that your Falcon is starting with cache and blitter ON
Cops.acc. Or patched xcontrol
Use only the patches and cpx supplied in Mikro archive, not the older ones, and don't mix different versions of Mint
If it still doesn't work, I don't see various options : Mint installation is corrupted or you have a hard drive issue. In this case repartitioning and or reinstalling NVDI and Mint from scratch may be the ultimate path. It may sound stupid, but I had this issue after several crashes too.