iPhone shows no pictures in Windows Explorer

When I plugged in my iPhone it showed up as a camera in Windows Explorer. But there were no photos. Against better judgment, I started the Scanner and Camera Wizard (Start menu, All Programs, Accessories). This is just a shortcut pointing to wiaacmgr.exe -SelectDevice that will assist in the copying process. But of course, it too told me "There are currently no pictures on your camera." Oops.

Windows detected the iPhone alright but showed no photos.
(Yes, I know, this is still XP, but there's a reason for that.)

The wizard told me what I already knew.

Turns out, I had one photo in the Camera Roll on my iPhone that was not taken with the iPhone camera itself (I believe it was a photo I saved from an email). As soon as I removed that photo on the iPhone, all other photos showed up in Windows Explorer just fine after I plugged it back in to my laptop. Actually, all that is needed is a screen refresh in Explorer.

Screendumps also cause this, so I typically email those to myself and remove them from the Camera Roll.

Bizarre.

But it works for me.

Begs the question why the Camera Roll isn't synced in iTunes to begin with. Doesn't seem any more complicated than syncing other data, music, and photos.

Edit May 12, 2011: the solution

By coincidence I discovered why this failed for me more often than that it worked. I have my phone locked with a code and the iPhone needs to be unlocked before it is plugged in or the camera roll folder will not be accessible. Unlock the iPhone, plug it in, and Windows Explorer displays the camera roll photos. Unlocking the phone after it has been plugged in does not work. If the iPhone times out while it is plugged in will still leave the photos accessible.

The reason it worked for me earlier after removing an unwanted image from the camera roll is because I unlocked the phone to remove the image. I just misinterpreted the removal of the image as the solution.