Crashes in release mode (ntdll.dll errors)

Hi, I would like to ask if anyone has encountered an ntdll.dll error/crash? I already created an installer for my Qt project and made the installer using inno setup. When I install and run the program, it goes well but it only crashes when I press the 'x' or exit button found at the upper right hand corner of the software.

I double checked my code and found out that upon close event, the destructor for my widget is called. I already commented this out, created another installer and run it but it still crashes.

what is ntdll.dll for?

thanks!

you dont need to worry about ntldll. worry about your code, which is crashing on cleanup - most likely means heap corruption!

use your debugger!