This script slightly modifies the _IsTradeAllowed function provided by http://articles.mql4.com/141

isTradeAllowed.mq4

//* ////////////////////////////////////////////////////////////////////////////////
// int _IsTradeAllowed( int MaxWaiting_sec = 30 )
//
// the function checks the trade context status. Return codes:
//  1 - trade context is free, trade allowed
//  0 - trade context was busy, but became free. Trade is allowed only after
//      the market info has been refreshed.
// -1 - trade context is busy, waiting interrupted by the user (expert was removed from
//      the chart, terminal was shut down, the chart period and/or symbol was changed, etc.)
// -2 - trade context is busy, the waiting limit is reached (MaxWaiting_sec).
//      Possibly, the expert is not allowed to trade (checkbox "Allow live trading"
//      in the expert settings).
//
// MaxWaiting_sec - time (in seconds) within which the function will wait
// until the trade context is free (if it is busy). By default,30.
///////////////////////////////////////////////////////////////////////////////*/
int _IsTradeAllowed(int MaxWaiting_sec = 300) {    

	// check for whether it's the "end of the forex day"
	// Pepperstone will not allow us to trade between 17:00 - 17:05 NY EST
	if ( Hour() == 0 ) {
		while( Minute() < 5 ) {
			Sleep( 1000 ); // sleep for one second
		}
	}

	// check whether the trade context is free

	if(!IsTradeAllowed()) {
        int StartWaitingTime = GetTickCount();
        // infinite loop
        while(true) {
            // if the expert was terminated by the user, stop operation
            if(IsStopped()) {
                return(-1);
			}
            // if the waiting time exceeds the time specified in the
            // MaxWaiting_sec variable, stop operation, as well
            if(GetTickCount() - StartWaitingTime > MaxWaiting_sec * 1000) {
                return(-2);
            }
            // if the trade context has become free,
            if(IsTradeAllowed()) {
                return(0);
			}
            // if no loop breaking condition has been met, "wait" for 0.1
            // second and then restart checking
            Sleep(1000);
		}
	} else {
        return(1);
	}
}