According to Microsoft this could be a bug based on what you may be trying to do. A such, one work around suggestion might be to use a Float data type rather than a Decimal:
However, as a first measure it might be best to install the Feature Pack for SQL Server 2008, service pack 3. It should be available as a 32- or 64-bit installer. I would suggest this first to see if it clears up your issue before changing data types.
I believe you would want your native client version to match the version of your server's database. Please try to upgrade the client (either 32 or 64 bit) to match the server and let me know if this resolves the issue.
What William was saying was, upgrade your SQL Native client on your workstation, to match the SQL Native Client which was already installed on your SQL Server.