Cannot load the remote project. The previous project suite was not closed

Hi,

   I'm running a distributed test suite using one master machine and two slaves. The master merely starts test routines on slaves and prints the logs. There are more than 300 tests in the suite and sometimes some tests would not start and I'm getting the following error in one (or both) of the slave hosts "Cannot load the remote project. The previous project suite was not closed". I'm not sure what this actually means and how to fix this issue. Can anyone help?

Thanks!

     Yuri