Jumping audio levels

We're working on a project with several TV spots on a timeline ready to dub. We carefully set all the audio levels where we wanted them.

As we play back the timeline to record to Beta SP for a station dub, some clips suddenly are overmodulating, like we'd kicked the level up 10db or more. When we go to that clip, adjust the audio gain to anything different, then return it to it's former level, the clip plays fine. This is happening randomly and intermittently. We fix one clip, then when trying the dub again, a different clip might suffer the same fate. Levels don't jump in the middle of a clip - it's either
the whole clip or nothing.

And it's not just in the monitoring - the Premiere VU output meters reflect this overmodulation, and then the proper levels once we make the adjustment.

The entire timeline has been rendered. Most of these clips have a "fill left (or right)" filter and the MultiBand Compressor set to "film mastering" applied.

I searched this forum as well as forums at Adobe but haven't seen anyone with a problem like this.

We're using PPro 2.0 (Production Studio Premium), with Matrox Axio LE (utils version 2.5), outputting via XLR to Beta SP. This is something we do all the time, but we've never see this before.

I wondered if maybe the Matrox board was acting up, but since the VU meters in Premiere (which are upstream from the Matrox board) reflect these wacky changes, it seems almost certainly a Premiere problem.

Thanks for any insights or suggestions.

Off-topic: When searching for keyword "audio" in this forum, selecting my time frame as "2006-present", the posts only go back two months or so. I'm pretty sure audio was discussed prior to that. Am I doing something wrong?

Larry Melton