Since all tablets are affected the problem is most likely due a loss of connectivity. If that is the case then starting a new event will not help. I would check the PC to see whether it is still connected to the wifi router's network. If it is not then try reconnecting it. If it shows that it is still connected then try rebooting the router by powering it off and on again.
BridgePal server can be shut down by clicking on its icon on the windows taskbar at the bottom of the screen (the icon looks like two overlapping phones or tablets with blue screens). Then click on the close box in the top right hand corner of the BridgePal Server window and confirm that you want to close down BridgePal Server. After this you should be able to restart wireless scoring for the same session from the scoring program - you shouldn't need to delete the event, you will lose all scores recorded so far if you do that ! I emphasise that it should not be necessary to close down BridgePal Server anyway, as the problem sounds like a network issue as described in the first paragraph above.
