Sorry this has happened, however the code file mentioned is not ours and the error is coming from the SQL Server connection libraries on the system, meaning there are probably numerous causes for this type of problem.
I would check that there are no uncommitted transactions on the database at the time, for one, using sp_who2. SPID 55 may be listed in the SQL Server activity monitor, so maybe that SPID has hung and needs to be killed off before generating data. You may also want to check Task Manager and see what Process ID 1504 is doing and break the process (provided it's not SQL Server's process.)
I hope this helps!