You know...Leopard came out after Fireworks CS3. Apps don't always run
perfectly on new OSs, no matter what platform. Many of my husband's music and
audio apps, that worked fine under Panther won't run at all under Leopard.

I have Vista and Fireworks runs well on it, with the exception of the bitmap
tools for which the Aero theme needs to be turned off. It's a workaround, not a
fix. Every new OS offers up this...er, adventure in application compatibility.
You have three options: drop back a level in your OS, hope for a bug fix, or
wait for the next release of the software.

To run his music and audio apps, my husband made his computer dual boot with
Leopard and Panther. You might try a dual boot with Leopard and Tiger or
whatever other OS you have available. Run Fireworks under Tiger and see if you
don't get better response.