Mac OS 10.7.5 + LC 4.5.3 + standalone question

[jbv at souslelogo.com]

Hi list,

One of my client is using Mac OS 10.7.5 and from time to time I send
him updates for a standalone made with LC 4.5.3
When he was on 10.5.8 everything was fine, but now the standalone
won't launch and the icon keeps bouncing in the dock... Furthermore,
setting GateKeeper to "anywhere" doesn't help.
Any clue ?

Thanks,
jbv