Adobe Fireworks is a pretty brilliant program for rapidly developing web layouts in a kind of best-of-both-worlds way that enjoys the benefits of both vector and bitmap design, without all the frustrations that come along with smart objects. Its text handling is also superb, offering a whole lot of customisable settings that are very useful for mocking up web designs, not readily available in either Photoshop or Illustrator.
However, it is not without its faults. On Vista, when typing text in Fireworks things can occasionally go very, very wrong. The solution at least initially is to turn off the “Auto Kern” option in the Properties dialog — but this removes one of the big benefits of using Fireworks in the first place!
There are other options. The problem will go away (sometimes) when the file is closed and Fireworks is restarted — this is hit and miss. More permanently, disabling Vista’s fancy-pants Aero theme (the thing that makes all window borders transparent, gives that snazzy Start + Tab effect, etc.) will ensure you have a glitch-free Fireworks font experience.
The real solution? Sneak into Adobe HQ and write a patch to fix the stupid thing!