Drupal trouble: underscores bypassed when looking for file names

I’ve recently come into trouble with Drupal in the last week or so. Many of the product images for my merchant site are no longer found. I looked at the source code and it appears that the generated code looks for those images, but for some reason it’s taking out all of the underscores in the file names. Of course this leads it to look for the wrong file.

Is there any setting that might have created this problem? As far as I know it worked fine just days ago, and I haven’t done much with the site recently.