Error: An item with the same key has already been added. 2008 R2 Nov CTP

I am getting a classic MS error "An item with the same key has already been added."

I am running 2008 R2 Nov CTP on Windows XP SP3 (VirtualPC: XP Mode in Windows 7 64 bit). I was trying to add new dataset in already existing report. While doing that BIDS is giving me this error. I've googled and found out that its a well known issue from 2005 but didn't know that this issue is not resolved completely. There is a hotfix for 2008 version 10.1.2531.0 (http://support.microsoft.com/kb/971049) . (Mine is 10.50.1352.12).

I've tried doing following.

1. build the project couple of times. (as suggested from one site)

2. Used text.

3. Created stored proc with the same text.

4. Tried to give different names for dataset as well stored proc. but no luck yet.....

Any more suggestion or fixes?....

Thankxxx......