SQL Developer

I'm trying to configure Oracle Advanced Security for SQL Developer. I'm using SQL Developer 1.5.1 (downloaded with the included JDK). When configuring the connection I select Connection Type: Advanced. My JDBC URL is:

jdbc:oracle:thin:@(description=(address=(protocol=tcp)(host=hostname.com)(port=1234))(connect_data=(service_name=DVLP)(SQLNET.ENCRYPTION_CLIENT=REQUESTED)(SQLNET.ENCRYPTION_TYPES_CLIENT=AES256)(SQLNET.CRYPTO_CHECKSUM_CLIENT=REQUESTED)(SQLNET.CRYPTO_CHECKSUM_TYPES_CLIENT=MD5)))

This works great in Linux. But on a fully patched Windows XP machine when I try to connect I get "Io exception: Checksum fail Vendor code 17002"

Note that this is only a problem with the thin client. If I use the OCI client (jdbc:oracle:oci:@....) it works fine.

Also note that the db to which I'm trying to connect is a 10g database with these sqlnet.ora parameters:
#ASO Encryption
sqlnet.encryption_server=required
sqlnet.encryption_client=required
sqlnet.encryption_types_server=(AES256,3DES168,3DES112)
sqlnet.encryption_types_client=(AES256,3DES168,3DES112)

#ASO Checksum
sqlnet.crypto_checksum_server=requested
sqlnet.crypto_checksum_client=requested
sqlnet.crypto_checksum_types_server = (MD5)
sqlnet.crypto_checksum_types_client = (MD5)

SQLNET.INBOUND_CONNECT_TIMEOUT_LSNR1251=120

# Require clients to be Oracle 10g or higher
SQLNET.ALLOWED_LOGON_VERSION = 10


Has anyone else seen this?

Thanks for your help!