No Dialect mapping for JDBC type: -1 when using SQL Server 2008 and driver 3.0

Issue

• We have a SQL Server 2008 database table that's comprised of several varchar columns, and two varbinary columns.  In our code, we're using entityManager.createNativeQuery(...) to query the varchar columns, and we're using Seam's injected entityManager to do it.  When the code is executed, though, we get the following error message in the console: 

  Caused by: org.hibernate.MappingException: No Dialect mapping for JDBC type: -1
       at org.hibernate.dialect.TypeNames.get(TypeNames.java:79)
       at org.hibernate.dialect.TypeNames.get(TypeNames.java:104)
       at org.hibernate.dialect.Dialect.getHibernateTypeName(Dialect.java:393)
  ...