I've been looking around a bit on the forums, and google, and I noticed I'm not the only one here with this same issue. Before I get flamed or modded for saying this is an issue related with DCC, please note that I'm fully aware of the flameware that happened on another thread involving this:

Please see thread:
https://forums.mirc.com/showflat.php?Number=124323

Towards the end of that thread, I noticed people started posting their machine specs, and amazingly enough, they were similar. I am having this same issue, and because I hate downgrading, I'll probably just have to deal with it for now, I can use another client for DCCing to my eggdrop. Anyways, I have reason to believe the access violation is due to nForce drivers not returning a handle to one of the processes mirc uses. Whether it be a permissions issue, or not, I don't know.

Anyways, all of the systems people had that were having this issue were AMD64 based, and a few mentioned having the nVidia firewall on. This is NOT a firewall issue where it is simply blocking the DCC, mirc is crashing due to some kind of pointer error.

I'd thought I'd post this in here, since no one seemed to make that connection in the other thread. -- Khaled -- if you need someone to test various executables on a machine where this crash occurs, by all means let me know.

Also, according to that other thread, it doesn't occur in 6.14, so that might help you track down the bug.

Thanks,
Sam