I have a pioneer dvd tower but my master DVD is an IDEO Sony.

Here is my problem:

I had a problem with a DVD that was 4.2 gigs and now if I burn another DVD lets say 400mb it still recognizes the 4.2 gigs. If I try burning the 400mb DVD it wil not say complete because it thinks the 4.2 gig DVD is in the try. However I do get a burn. But this is driving me crazy.

Any help....how can I reset this bad boy?

Thank you,
Randy