We all have dumb clients, I seem to have my fair share. Recently came across a problem when using images as CSS backgrounds. Took me a while to track the problem, but the client was uploading files with brackets in the filenames, causing the css to freak.
For example img_0599-(1).jpg uploaded in CMSB,
I know that you strip out spaces and replace with dashes on file upload, could you not add to that a routine to strip out brackets as well.
It may not crop up again, but it won't for sure if you do this.
This may be an issue that can be resolved in the CSS itself, as it should generally be possible to use images with brackets in them. Could you give me an example of the code/CSS you're using to add the image as a background?