Many thanks again Lyndel,

I think I've found a solution, I have modified Sebastian's HA script that I'm also using for sending Battery and WiFi status from my Prontos to HomeSeer.

/*!
@title test10.v-fischer
@version 1.0
@author v Fischer
*/

var updateInterval = 60 * 1000; // 1 min; in msec

function getDate() {
d = new Date();
return d.getFullYear() + "-" + ("0" + Number(d.getMonth()+1)).slice(-2) + "-" + d.getDate() + "T" + GUI.getDisplayTime() + ":" + ("0" + d.getSeconds()).slice(-2);
}
function time() {
var timePattern = new RegExp('(\\d+):(\\d+)((am|pm)*)','g');
GUI.getDisplayTime().match(timePattern);


var hour = parseInt(RegExp.$1,10);


var minute = parseInt(RegExp.$2,10);


if (hour === 3 && minute === 55) {CF.widget("A4","B","C").executeActions();}
var ampm = RegExp.$3;
var seconds = new Date().getSeconds();
}


/*
schedule periodic updates for when the TSU sits in the charging dock
and it is powered on.
*/
function periodicUpdate_2(activity) {
System.setDebugMask(9);
System.print(getDate() + " [ScheduleAfter] TIMER");
time();
activity.scheduleAfter(updateInterval, periodicUpdate_2, activity);
}

((function () {
//debugging
System.setDebugMask(9);
// the current activity.
var myActivity = CF.activity();
myActivity.onEntry = function () {
last = System.getGlobal('time_last_update');
ts = Date.now();
if (last === null) {
System.print(getDate() + " [Wake up]");

time();

System.setGlobal('time_last_update', ts);
}
};
System.print(getDate() + " Setting up scheduled updates for TIMER");
myActivity.scheduleAfter(updateInterval, periodicUpdate_2, myActivity);
System.print("Done.");



}()));

I'm using onEntry to kick off the new timer.

Will do some more tests, but it seems that all is working fine now.
I'm using the stuff to put the sunrise/sunset data into Schmuzli's Prontotimer because the weather.com data aren't available nomore.

(BTW: Barry's Pronto Pro Debugger shows 'Action list error' but that can be ignored)

Thanks,
Fischi