Check with the webservice provider and see if either A) they can accept compressed strings and can uncompress; or B) if you can break it down into smaller chunks.
If you are invoking the web services via a GET request, many servers can be setup to prevent GET requests of certain lengths, however, most allow moderate 20MB+ submissions for a POST.
Are you able to POST data to the web service instead?
Thanks for your recomendations, The problem is still there. I'm doing a POST.
I already did the same sample in CF9 and I don't have the problem there. The only diference is the that the CF9 is a physical server with Win Server 2008 R2 and the CF 10 is a virtual with WIn Server 08 R2.