Since someone mentioned me by name, I thought I'd jump in for a minute...
First and foremost, you need to make sure there is no inadvertent ground fault in your system. Lots of ways to do that, which have been covered here before.
That said, the Trace SW series will trip GFCI outlets all by itself, even with no ground fault. This is due to a filter capacitor. I wrote about the solution extensively here:http://www.busconversions.com/bbs/index.php?topic=3285.msg29365#msg29365
Once you've ensured there is no real fault, and removed the green strap inside the case (which is NOT a ground/neutral bond and NOT a case ground) that I discussed in that post, you will STILL have a problem from the ground/neutral bonding relay that should have been installed along with the Trace. I discussed that issue here:http://www.busconversions.com/bbs/index.php?topic=16322.msg175595#msg175595
Lastly, even if all the above have been covered, your front-end power management and monitoring may, by itself, trip the GFI. All I can say here is you can either live with it, or bypass the monitor. Without seeing a schematic I can't say for sure if this is part of your problem.
Hope that helps.