You can search in the registry for entries that contain "med.exe", and then remove the key.

However, this is probably not the reason for a MED problem. MED isn't the reason either, as MED obviously works for all other people and the same MED even works on his machine in his Gamestudio installation. So I guess it's something special in his the lite-C installation. When someone else runs into a similar problem we'll might find a common cause - until then I'll have to leave it at that.