I've been working on this for about a day and a half now, and searched numberous blogs and help articles on the Web. I found several questions on SO related to this error, but I didn't think they quite applied to my situation (or in some cases, unfortunately, I couldn't understand them well enough to implement :P). I'm not sure I can describe this well enough for help... but here goes:

We have a .NET app to track our resources. There's an export function to copy a resource to the time tracking system and the billing system; this accesses a stored procedure that links to the time and billing databases.

I recently moved the billing system database to a new server (original server: Server 2003 SP2, SQL 2005; new server: Server 2008 R2, SQL 2008 R2). I have a Linked Server set up that points to the 2008 databases. I updated the stored procedure to point to the 2008 server, and then I got an error about MSDTC and RPC (http://www.safnet.com/writing/tech/archives/2007/06/server\_myserver.html). I enabled 'rpc/rpc out' on the Linked Server and set MSDTC to allow Network Access (something like this: <http://www.sqlwebpedia.com/content/msdtc-troubleshooting>).

Now I'm getting the above, when I try to run the export function: "This SqlTransaction has completed; it is no longer usable." What seems odd to me is that when I just run the stored procedure (from SSMS), it says it completes successfully. 

Has anyone seen this before? Have I missed something in the configuration? I keep going over the same pages, and the only thing I found was that I didn't reboot after making the MSDTC changes (mentioned in here: <http://social.msdn.microsoft.com/forums/en-US/adodotnetdataproviders/thread/7172223f-acbe-4472-8cdf-feec80fd2e64/>).

I can post part or all of the stored procedure, if it would help... please let me know.