Why are msoclip1 (png) files appearing in trash..

[spinifex67]

Almost on a daily basis, when I shut down my G4 Mac Laptop running OX
10.4.8 and Office 2004, I am getting hundreds or thousands of files in
the trash the next day. They are in a folder

Recovered files-msolip1-01

and the files are:

clip_image001.png
clip_image002.png
clip_image003.png

Opening each one shows a black bar or a colored bar...

Any ideas on what could be causing this? Usually I am using Excel,
and I am likely shutting down the computer before quitting Excel, but
I do not have any files open or unsaved at the time.

Thanks,
Jeff