Some files not going into nero



ok so i have a recorder that records in .asf. and most of the time it will allow me to input the files into nero so i can make a dvd but some times it says “Unable to insert C:\Documents and Settings\Name\My Documents\CLIP0001.ASF”
When i spoke with bestbuy they said it might be a codec issue but i cant find a newer .asf codec.
Now i can watch all of these videos on my computer. The only differnce is that i cant advance the film at all.
If you have anyideas please help me.
Also im pretty new to this stuff so please keep that in mind when trying to help. thanx again