Hover over its thumbnail in the grid view? Or in the full-screen (loupe) view?
What kind of mouse is it, is it the magic mouse? I could maybe see where sporadic scroll input could be a possibility there but if it's a mouse with a more traditional wheel, do you have scrolling trouble in other applications?
Ruahrc
Loupe view, not grid.
It's a Logitech MX620, one of those with a scroll wheel that also tilts for horizontal scrolling. I think it's the culprit. For whatever reason, it doesn't cause this problem in Aperture, but it does in Lightroom, so long as I have the smooth scrolling enabled. Switching it over to "microgear" scrolling (via a hardware switch on the bottom of the mouse) seems to have solved my problem, although I prefer the smooth scrolling for all other applications.
While I have the eyeballs of some veteran Lightroom users, perhaps someone could help me with another little problem. Is there any way (besides the View Options-->Show Info Overlay) to see some basic EXIF info at all times? Whenever I'm in Loupe view or in Develop, I can no longer see what exposure and ISO I used, unless I manually change my second monitor each time to be in Grid view. Right now I have that Show Info Overlay active, but the font for it is huge and obnoxiously superimposed upon the image itself: blech!
Alternatively, is there any way to change that obnoxious font size? Even the the smaller of the two sizes available is still very large.
I miss Aperture's option to have an EXIF "HUD" open at all times.