Have you recently installed a printer? My problem was related to a printer that was causing a problem with the /Windows/twain_32/ folder. " Every time computer imaging software is used to access photos from a digital camera or images from a scanner, TWAIN drivers are in the background making it all possible. The TWAIN drivers that allow imaging software to understand the information located on an imaging device are a common part of a computer user's experience, yet often go unnoticed until a problem occurs."

Read more: What Is a TWAIN Driver? | eHow.com http://www.ehow.com/about_5282752_twain-driver.html#ixzz1zNzH7sGQ