Motherboard and storage (SATA, and USB if relevant) drivers are also highly relevant here.
In the past we've seen BSOD caused by bad motherboard drivers that didn't like the way we updated our progress dialog while a lot of data was being written to disk at the same time. It could be an issue like that. Those issues affected other software as well, but happened more when Opus was copying files, since Opus happened to do something that was likely to trigger the issue. Updating the motherboard/SATA drivers fixed the issue in that case.
If you're seeing BSOD when Opus isn't running, even if you're seeing fewer of them, then there's a deeper problem with the machine than anything Opus itself could be causing.
(There may also be an issue with Opus, if the two things are not related, of course, but I would fix the BSOD first, since it needs fixing either way and may resolve both issues. Fixing BSOD is probably beyond the scope of this forum, but if you can tell us some details about it we may be able to help. BSOD usually have a "stop code" which tells you the nature of the error, and sometimes also point to a particular driver/DLL/SYS file, for example.)
What's memory usage like in Task Manager's Performance tab just after reboot vs after a couple of days? If system memory is being exhausted, that could be causing some of the problems. We have a guide on tracking those down, but it's only worth looking at if it looks like that's the issue: