Task Sequence Failing with Hash Value is not correct

Just wondering whether anybody can assist. I have been trying to build a new image, pretty much trying to unerstand the concepts from the various sources on the net, such as this one. I have had some assistance from anyweb (thanks). But now that I am at the final straight, I again have hit a hurdle.

The environment is Server 2008R2, SCCM 2007, SQL 2008, Windows 7 Ent.

I created 2 Build and Capture TS , one for 32-bit and another for 64-bit Windows 7 Ent, using VM

I combined the 2 wims to create a combined wim. I used DISM to mount the image and IMAGEX to append the image.

I created package, advert and collection, updated the DP, etc about 6 times, everytime recreating a new package/ad. The problem I am experiencing now is that the TS keeps on crashing with the following message;

"Failed to run the action: Error in the task sequence.
The hash value is not correct. (Error: 80091007; Source: Windows)"

I have attached a copy of the SMSTS.log file, from \windows\temp\smstslog\

Any pointers very much appreciated.

thanks