JPEG Previews Lost

Windows 98 SE, 256 MB RAM, Pentium 3, 12gb HD, ZoneAlarm Security Suite, Browser: FireFox 1.5.0.8, IE 6.0, Spyware Blaster, Spyware Guard, MRU Blaster, CCleaner, EmptyTemp.Folders, SpyBot, HiJack This...

I downloaded JPEG images from my digital camera to another computer (MAC) using Kodak Easy Share software. Then e-mailed them to myself, opened in my computer and saved to C:\my documents\mypictures. I have Easy Share software on my computer but do not use, prefer QuickTime Picture viewer & Lexmark (X-4250) all-in-one software for editing.

The Rub
When I saved, Easy Share converted all of my picture files (JPEG, GIF, BMP..) to Easy Share from QuickTime. When I attempted to convert them back I lost the ability to preview JPEG images and lost ability to view movies using quicktime. GIF & BMP still preview.

I have gotten no where trying Folder Options & QuickTime Preferences, QuickTime Updater, Norton Un-erase...
I use CCleaner & MRU Blaster several times a day and Empty Temp-Folders whenever I'm forced to use my IE browser.
Can anyone tell me how to get this Preview Pane function back.
Please be a gentle.