Most probably a driver issue. Go to ASUS pages for latest drivers, download them and, preferably uninstall old drivers... not necessary, really, then install the new drivers. You can also use your original drivers disk, but usually new ones are an improvement.
There seems to be some differences between Western and Asian computers, be careful to pick right model.
And, if the problem only occurs with one or some file types, it may also be a codec problem.