Thanks for the feedback. Unfortunately I am unable to set a screen size as large as yours. If you were unable to reproduce the issue at my resolution, it seems that I will not be able to reproduce it.
That said, I have checked all of the code relating to the window position reset feature and have not found any limitations on window position/size.
I have set mIRC's horizontal window width at both below and above the 1040 pixel width you mention, placed the left edge of mIRC's window at the left edge of the desktop, saved and reset the window position, and it worked correctly for me, so it does not look like it is related to the window width since that works for both you and me at larger widths on lower resolution desktops.
At this point, the only cause I can think of is a display driver bug. However, if anyone else on the forums can reproduce the issue, that would help narrow it down.
