Thanks for your bug report. I cannot seem to reproduce this issue here. I have tried placing the mIRC main window left/right sides flush/not flush with the sides of the desktop and saving/resetting position and it has worked correctly for me. That said, my desktop is 1440x900.
If you change your display size to 1440x900 or thereabouts, do you see the same issue? If you do, can you describe a step by step method that you used to reproduce it?
Note that Windows does not position/size mIRC's window when you run mIRC - mIRC does that.
