No matter what type of SQL Server Maintenance Plan you create and no matter what credentials you use, the plan always fails with "Execution Failed." There is almost no information to go on either. Event logs, SQL Agent logs....nothing is reporting a problem.
Are you using SQL aliases?
Make sure you've set the alias for both the 32bit and 64bit drivers. We ran into this exact problem and as soon as we added the alias to the second section, all the maintenance plans ran fine.