I've just installed a new MS Intellimouse Explorer 4.0 on my PC, and for some reason, the scroll wheel won't function in mIRC. I can roll that wheel all day long, and there's no scrolling in the channel windows.

When I use my old mouse (an older version Intellimouse Explorer), it works fine. I've installed the drivers and software for the new mouse, and scrolling works perfectly in other applications.

Other details:
OS - Windows Vista Business
mIRC - v. 6.21

Is this (another) Vista compatibility issue? Just a MS issue? Anyone encouter anything like this?