PCAnywhere host keyboard input hangs

I am using PCAnywhere 8.0 to connect to a 5.0 DOS host. Periodically, the host will stop processing input from the serial (modem) port until a key is hit locally. Then, suddenly, all the keys typed by the remote come flooding by. They connect directly through modems, and the connection does not terminate. From the windows side, the keystrokes seem to make it across, as there is modem activity when the keys are hit.