I'm getting the following error when trying to connect to a Sql Server (2005) using JDBC:
unhandled token type: unknown token: 0x53
Any ideas anyone? I would have liked a more descriptive error too!! Also, I've done the 'telnet servername 1433' test and can confirm that machine can create a TCP connection.
Sounds like you're using an old driver for the pre-2005 SQL protocols. You need to use the new JDBC Driver for SQL 2005.
As an alternative to the MS dirver you could also try jTDS. I've had good experience with this driver on SQL Server 2000. The project page states it is also fit for SQL Server 2005.
In the end, the cause of this problem was that we had mirroring turned on. So, to solve it without upgrading the driver we had to turn off database mirroring. But, since this is a kludge really, a better idea would be to use a better driver, i've marked that other answer as the solution.