PAL to NTSC Audio Conversion - output problem with BeSweet

[Oni]

To make a DVDs of varying formats, I needed to get them all NTSC compatible to produce in Ulead DVD Workshop. So, I took my main 25fps, 320x240 video in VirtualDub and extracted the .wav with Direct Stream Copy. This gave me a MP3 Wav file of 44.1k and the sound was fine, if not a little muddied.
Then I went into BeSweet and did a 25-23.976fps conversion in PCM.
The wav file for the most part plays fine and syncs up well when I interleave it into the now 23.976 .avi video. However, during at least two very noticable segments, I hear this consistant popping sound (like the signal is coming in too hot, although all I'm doing is converting an already recorded signal...). The similarity in these two events is a guitar's feedback rising and mostly scilence otherwise. (The source video is a concert.) It could be that the popping sound is always present during more active moments but just too soft to be heard or that it only occurs during the source's feedback.
I really don't know what to do for this problem. I've converted the MP3 Wav file to 23.976 PCM a few times with no noticable change, so I'm sure it is a problem contained within only BeSweet. Should I try to edit out the popping in SoundForge? I think I will only make it worse that way. I was hoping this is a common problem...
Any suggestions? Other programs I should try, other formats I can extract from virtual dub to make this work?

I would appreciate any help if any of you might know what's going on...
Thanks.

[Oni]

Sorry, but I actually have fixed this. I found an old PCM copy I did of the .avi from VirtualDub and used BeSweet on that.
Against my better (newbie) judgement I followed bad advice from a tutorial here. Ehh... anyway, the MP3 compression from VirtualDub was at fault, and the subsequent decompression to PCM which at that point was working with audio that lost too much information...