Generating previews of JPG files

[rrn]

OS = Windows 98.  Windows Explorer "views" is set-up as "a web page."  Until last week, when JPG files were single-clicked on (highlighted), message that "generating preview" and then thumbnail of jpg would appear.  Suddenly, the "generating preview" / thumbnail has stopped working for jpg files.
However, this feature is functional for gif and html files.

Any ideas as to why it's not functioning for jpg files?  Most of my saved photos are jpg and I don't want to switch to other formats.

Thanks for any light you can shed on this problem.

RRN

[Flame]

Have you installed any new software lately, or mad any changes to your system?

[glb]Flame[/glb]

[rrn]

No new software installed; no changes to system -- unless something was done accidentally, as my fingers move quite rapidly across a keyboard.

Although most recent "change" made -- when quick-time "took over" as default jpg files viewer and I changed the default back to Corel PhotoHouse and changing its icon back to PhotoHouse as well.

Thanks.