1.5.4 - jpg upload no longer working

[eluser]Neovive[/eluser]
I have a test CI application on my Windows development machine that utilizes the code from the CI user guide to perform image uploads. The script runs fine in 1.5.3, but no longer uploads a valid image in 1.5.4. The uploaded image appears to be the proper filesize, but is not viewable in Windows and is not considered a valid image when using the CI Image Resize functions.

When I copy the original 1.5.3 Upload.php file into 1.5.4 it works fine.