Try uninstalling Picture It! and reinstall it again.
If that doesn't work, then download Unlocker
Also install the context menu handler.
Right click on the Picture It! executable, not the shortcut, but the target of the shortcut.
Choose Unlocker and tell me if any processes are locking the file. Don't press Unlock All unless you are sure the file is ok to be unlocked. I once tried unlocking a drive and it crashed my computer.
EDIT: It may just be the file permissions though. Post this in the Vista forums
I don't think this is the right place for your question.