Let me make a few things clear:
This only happens occasionally when manually scrolling up in a window. I'm not talking about when someone speaks in a channel which causes all text to "scroll" upward. I'm talking about using the mouse wheel or scroll bar to scroll up in a window to view lines that are no longer visible in the window.
When the problem occurs, moving the mouse cursor does not change the behavior. I am well aware of the way mIRC does not update the mouse cursor until the cursor is moved even if the text below the mouse cursor changes due to scrolling. This is completely unrelated!
I do not modify mIRC's default channel output at all. I use only a very small amount of scripts that I myself wrote. Other than changing the font to Tahoma, you'll notice the screenshot I gave is standard mIRC output. I don't have any ON HOTLINK events. I'm running Windows 7 64-bit.
