I have been having a similar problem

I actually had Piconews running on my ATT 8700 using the BIS and everything worked fine.

As I changed jobs I switched to ATT Curve and tried loading Piconews again.

This time I got the error:

Piconews platform:Blackberry
Version: 2.11
Blackberry PIN: XXXXXXX
Step: Configuration
Error: Error while parsing response (10005)
Details: Exception (Timeout?):java.io.IOException:incorrect header check