|the exception you're getting is probably when executing SQLCommands using "ExecuteDataReader" and openning the datareader while another data reader is already opened in another thread.
example of creating the exception:
thread 1 executes:
SqlDataReader dr = LocalSqlCommand.ExecuteDataRead();
in the same time thread 2 tries to execute the same symmantec:
SqlDataReader dr = LocalSqlCommand.ExecuteDataRead()
dr.Open() -> this will generate the exception...
its a .NET limitation to open only one DataReader per application !!!
- always close the dataReader when finished by executing: dr.Close()
- try raising a flag between threads (mutex) so they block each other while they open and close DataReaders