A common error when deploying a MDT 2008 generated Task Sequence for SCCM 2007 is the following error:

Task Sequence: has failed with the error code (0x80091007). The full error is "the hash value is not correct".

Workaround:
One common solution is to change the advertisment to access content directly from a distribution point when needed by the running task sequence, but that's really not needed...

Instead, most times it's the Settings Package that is failing and you only need to Update the Distribution Point for that package and then everyhing works just fine...