Desktop icons gone

[David Shochat <shochat acm org>]

I must have done something that caused the icons for most of the items 
on the desktop (namely Trash, ldp, helixcode, gnotices, gnome, cdrom and 
fd0) to lose their distinctive icons and revert to generic "sheet of 
paper" or folder icons. I tried creating a new user account with an 
empty home directory, and it had all the distinctive icons and slightly 
different names. But I can't figure out what is different between my 
configuration and this new user configuration that would account for 
this. Both seem to have identical .gnome-desktop contents, for example. 
So what determines the actual icons and names for those items? Two of 
the items do have the proper icon on my desktop, namely Bug Report Tool 
and Helix GNOME Update. But I can see how those two are controlled by 
bug-buddy.desktop and helix-update.desktop in .gnome-desktop. How are 
the icons and names for the other things determined? More to the point, 
how do I fix this?