Do you have any scripts installed? Can you reproduce this in a clean install of 7.1? The issue looks similar to this report, which was "solved" by using a clean install.
Did a freash install on another computer and didn't have the same problem. Must be conflicking with the old versions settings, as I have no scripts enabled.
Thanks for the bug report - it would be really helpful if you could zip your current mIRC folder and settings (take out any personal details first) and email it to me at khaled@mirc.com. I will try to reproduce the issue to see if can find out what was causing this.
This problem occurs with me too. Maximizing the window makes the problem go away as well as resets the location of the text to be "normal" but once the window goes back to its usual size, the problem begins occurring again.
This problem occurs for me in every window that I'm currently not focused on.
If you can zip your current mIRC folder and settings (take out any personal details first) and email it to me at khaled@mirc.com, with a step by step description of how to reproduce the issue, I will try to track down the bug.