Strange preview problem

Hi,

I'm using CR10 to generate report from VB.NET app.
There are three reports with similiar layout, and I just copy one to another during development.
The first two reports can be printed w/o problem, however, for the third report, when I preview or print, I got an error:

"Error in File C:\DOCUME~1\STM\LOCALS~1\Temp\{7D7683BA-C0E3-4144-A1A4-0E2A9AD69929}.rpt The request could not be submitted for background processing."

This report just accept ADO XML as datasource, and there are no difference in the 3 reports except the layout.

Anyone know what is the problem and how to solve it?

Thx!