Thumbnail view option missing from menu

For some reason, I no longer have an option on my view
dropdown menu for thumbnails. The thumb.db file is still
there in the folder. I can view previews of pictures when
I view a folder on web view. But no more thumbnails and
no way to turn them back on.

Doing regsvr32 thumbvw.dll did not fix the problem.

It would seem to me that something has changed in my
registry. I once lost the ability to create new folders
as the "new" command disappeared from my menus after a
video driver update on this same box. I had to reset a
registry entry to fix that.

I have some concern that the recent critical update may
have disabled this funtionality, because when I updated a
box that has 98 on it, I can no longer view or choose to
view thumbnails there either. If I try to enable
thumbnails on that box, the file changes to read only, the
icon for it becomes a briefcase and the folder will not
open at all, let alone allow for the viewing of thumbnails.

Any ideas?