We have not realized you are still on .NET CF 1.0 - that might really complicate things a lot! The last version of Rebex SFTP to support .NET CF 1.0 was 2.0.3723.0, released in March 2010 (1.5.3127 was released in July 2008). This might solve the issue, but it's by no means certain.
If that doesn't help, the next possible solution would be a backport of the current version of the SSH library (most likely responsible for the issue) to .NET CF 1.0, which is not a trivial task, but almost certainly can be done in a day or two.