I'm currently running NB on an older XP-64 computer that has a damaged CMOS. I runs it headless, and I just press the F1 to continue when it requires a re-start. The consequence of this is that it defaults the date to 2010. I recently had a DB problem with a rather large group, and had to purge the entire group, and rebuild it. I have empty groups set for one day, but because of my RTC being wrong it downloaded the headers back as far as they go. The main drive ran out of space after a few days. That's when this annoying popup became terrible.
Even though it pauses regular downloads, the headers continue to download eating additional space. Pressing OK, is immediately replaced with the same window with no chance to shut down NB so it makes the low disk space even lower. I could not get to any of the desktop behind the NB window either, which just seemed wrong to me. It used to delay a few seconds before it returned, but maybe due to the SSD drive that delay has become zero. The only way to shutdown NB when this happens is to kill the process or reboot the computer.
Anyway, as I've figured out why it was downloading more than 3000 days of headers, instead of just one, it's no longer an issue for me, but I sure wish that pop-up would just go away when I press OK until the next time it passes the low disk space threshold.
I hate windows. I'll be moving to Linux after I work a few issues out. (QEMU, separate vlans, Static IPs, etc.)