MPEG-4 problem

[bdtay]

I am using the DVD Express program to convert VHS to DVD which is actually an MPEG-4. I have no problem with the conversion and the resulting file plays just fine on my computer ( when the file is on the hard drive) and I am having no trouble with the burnt disc playing in my DVD player. The thing I can't understand is if I take the resulting disc and try to play it in my DVD player on my computer then the file is unrecognized. In fact when I insert the disc into the DVD drive it locks my whole computer up. I was thinking it was a codec problem but then why does the file play just fine from the hard drive? Any help is appreciated.