reason 4 and ableton 6 recording out of sync

[Audio Dependent]

i use reason as my main production tool and once i have a song in reason i record all the elements into ableton so that i can add it into my live set. i've only fairly recently upgraded to reason 4 and i have hit a problem when i do this. when i record a sample into live through rewire i get a small section of silence at the start of the sample and hence all the new samples are slightly off on the timing. i'm running a macbook pro, novation sl zero and an edirol FA 101 and i've tried syncing to the internal midi clock, and the sound cards midi clock but that doesn't seem to change anything. is this a problem with the latency settings? or a specific issue with reason 4 - i never had this issue with 3. if there is no way to get rid of the issue whilst recording, is there a way to adjust the start point simultaneously for all samples? i don't mind re-syncing one sample, but if i have to do this to all the clips it will end up being a laborious and slightly unpredictable task.

cheers in advance for any suggestions anyone has.