Computer freezes after some downloads

[Cloim]

Sort of odd. Doesn't happen a lot, but just occured twice.
First time it happened, while running Mozilla, I select an image file for download (appx 1 Mb), the image saves to disk, then cpu monitor shows 100% activity, and nothing works except my mouse.
Then, simmilar circumstances except keyboard continued to work and gnome-panel continued to work.
Today I was running Konqueror, the file sizes were much smaller, and lost everything except mouse then later Xine continued to run on a different workspace (I could hear it but couldn't switch to it).
Using gentoo 1.4-rc1, Sawfish, Gnome.
Hasn't occured with anything except images, but has now occured with two different browsers.
The images did save to disk. And my reiser file system appears to have survived the hard shutdowns.
I have no idea where to look for a solution. Anybody have any ideas? Other than "don't download images"?

[B_F_Skinner]

Could be your window manager. Try switching to another WM and see if you still have the same proble. I had probs with sawfish before.