To make a long story short, I replaced a motherboard cuz it went bad. Everything works fine now except the CDRW drive. I have a few, so I tried each one, but none work except a standard CD drive. I can't imagine all are bad. And the CDRW drive that was working, doesn't. I get an error message "D:\is not a valid WIN32 application". Application CD's don't work, although data cd's do. At a loss, thanks for any help.

Not a valid Win32 application. (http://www.computerhope.com/issues/ch000726.htm)

reinstalled Windows, everything is fine. Must have had a missing file.

Wouldn't it be nice if all fixes were that quick? :)

Hang on!
There IS a way to do that [produce a quick software fix].
Except where you change the hardware. :(

You MAKE IMAGE BACKUPS.
Then when there is any hint of a software problem you restore a recent good backup image.