I've mentioned previously my admiration for Firefox 3, VMware Fusion, and the MacBook Air -- the last with some limits, since its elegantly stripped-down design makes it great for traveling but too limited (in disk space and ports) to be a "main" computer.
These three elements are very good individually and even better together, with one exception. Since the release of Firefox 3, I've found that running it at the same time I'm running Windows programs under Fusion, on the MBAir, frequently leads to a video-corruption problem that makes the screen look like this:
It doesn't happen if I'm using Firefox without Fusion, or using Fusion without (native Mac) Firefox. Unfortunately, Firefox and Fusion (which allows you to run any Windows program) are two programs I use all the time. When they're running at the same time and I am switching from one to another, sooner or later I will have this problem. It doesn't cause lost data, but it means a tedious chore of closing down and backing out of programs when you can't see what's on the screen. The menu bars still are visible, and work, but you have to guess-remember what the on-screen dialogue box is saying as you close each program.
VMware claims this is an (acknowledged) Apple video bug in the MBAir, and that Apple will some day fix it. I haven't asked Apple's side of the story. I mention it just for the record, as the one and only serious instability issue I've had with the MBAir, and as part of the continuing quest for de-bugging our technological lives.