I actually know exactly how to fix that - it is an issue with the WMP plugin that runs media codecs at the base layer of most media on your computer. The easiest, cleanest way to handle it would be to reinstall/reimage Windows 7 on the laptop, but if you're not comfortable doing so, try entirely removing WMP from your computer and reinstalling it. Other media players may help, but since WMP provides plugins for internet explorer and other programs, the issue will still exist in those regards. I highly recommend VLC as a replacement for WMP for any type of media, whenever you are able to use it - phenomenal, and free, program.
Seeing as the uninstall/reinstall tact was unsuccessful earlier, it very well may not work once again. At that, first check for any and all Windows updates, optional ones included, and install them all. Sometimes this can fix little registry and program issues. If that still doesn't help, you are best to go ahead with reinstalling Windows 7 clean. I've seen similar issues happen many times in laptops that are offered upgrades via the manufacturer. Software upgrades are great, but operating system upgrades on a busy, live system are a recipe for disaster, and always seem to leave some problematic remnants from the previous OS.
Please let me know if this helps, and if there's anything else I can help you with on it. I work in tech support, so I do this sort of stuff just about daily.
Regards,
Thomas