I have a Logitech LX3 optical mouse that was starting to have trouble with the scroll wheel, and I figured either the driver was hosed or the mouse itself had just worn out (it's probably about a year old, maybe two). Then it completely quit scrolling at all yesterday. This is quite annoying when you've become used to scrolling pages by rolling the little wheel and have to start using the window's scroll bars instead.
Luckily (for I loves me my LX3 optical mouse) I had a spare that I normally carry with my laptop. So I swapped them out and set the old one aside.
Today I started wondering if the damn thing was just full of cat hair. So I picked it up and took a look. It seemed from just a look through the wheel slot that hair might be the culprit. Getting an LX3 apart is non-obvious unless you've dealt with this kind of thing before, and sure enough, there were three screws underneath the three slider pads (actually just shiny black stickers) on the bottom of the mouse. Figuring I wasn't going to get warranty service anyway, I pulled the pads back, undid the screws, popped the case open, and sure enough -- there was enough white cat fur in the scroll wheel to make another cat.
Carefully cleaned it all out, screwed the case back together, plugged it in...and suddenly the scroll wheel works. Whee!
Saved myself $25, but I think I'm going to buy a couple more LX3's to keep around for spares anyway. It really is a fabulous mouse, and the bonus is that it doesn't have all the extra buttons on it that I keep hitting by accident whenever I use one that does. (E.g., recent iterations of the Microsoft Intellimouse, and more upscale Logitechs.)
I actually prefer the Logitech VX Nano for my Vista notebook. It does have a couple of totally unnecessary geegaws, but I hate to use a wired mouse anymore and the Nano has easily the most elegant design I've ever used for a wireless notebook mouse.
I changed to it from the brilliantly named "Microsoft Wireless Notebook Optical Mouse 4000" (attention Microsoft, naming is a place where less is better), and the Nano is superior in every imaginable way.
I have a Microsoft wireless travel mouse (another spare that I carry with the laptop; it's smaller and fits Sally's hand better) but I'm perfectly happy with a corded one, as long as a cat isn't sitting on the cord.