Error when trying to run cvs through Runtime.exec()

I usually use WinCVS, but I'm trying to write a Java app to automate some of the build/deployment tasks. If I run cvs -n update from the command line, I get the results of the query. If I run it via Runtime.exec() I get the below error. Any ideas? Running on a Windows 7 machine.

cvs update: warning: unrecognized response 'error: Failed to create SSH connection server' from cvs server
cvs update: warning: unrecognized response 'error: Error (0x80090006): Invalid Signature.' from cvs server
cvs [update aborted]: end of file from server (consult above messages if any)