If I remember correctly there were a couple things that could do this.
Check your desktop settings for the icon and text sizes. If they are anything but 100% or 125% then it will affect the size of the game window. It's some "accessibility options" thing or whatever to help visually impaired people or people who just like larger icons and text on their high res small screen. It just doesn't play nice with City of Heroes. Windows is weird that way.
Are you in windowed mode or full screen?
If you are playing in windowed mode and can click the title bar of the game window then drag it to the left so you can click the "maximize" button in the upper right and it should snap it to the same size and resolution as the screen.
Make sure the resolution the game is set to is the same as your desktop resolution and that the scaling slider is set to the same resolution also.
That did it! Thanks. I had my icon size set to 150%. I reset it to 100% and all is well.
Glad to help.
I just installed GR complete collection on my Sony L Series laptop. When I loaded the game to play, the sign-on screen was too big for my screen. The resolution is 1920x1080. The login portion of the screen was not where I could enter my information. Is there anyway I can solve this problem? Once I can log in, I can set the graphics, but I can't even log in the way it appeared on my screen.