Extremely slow when accessing file browsing dialog

Java programs on my computer run extremely slowly when accessing file
browsing dialog (Open, Save As, etc). Sometimes, if a program does
this repeatedly, it is fast after the first time.

This problem exists for my own applications, and for things I've
downloaded (pdfsam for example). It is a problem with my computer
setup. This problem did not occur in the past, I am not sure when it
started. When I run the programs on other computers, they run fine.

I have tried installing all the updates to my OS (Win XP Pro), and
have re-installed the JVM a couple of times. I am running the latest
Sun JVM.

Does anyone have any suggestions for tracking down or fixing this
problem short of re-installing the whole computer?

TIA,

Rob
.