It probably isn't breaking the validation... it is probably breaking the file upload. Windows doesn't allow files to have quotes in them, so I can't even create one to test with until I get back to my MAC.
I'd maybe use regular expression validation instead and only allow numbers, letters, and the period for the extension. I think the issue is that alphanumeric validation is for validation on sentences or paragraphs and it allows things like single quotes which shouldn't be in file names.