[Qgis-developer] segmentation fault in plugin using zoom tool

[nitin quick]

greetings developers,
i am currently coding a plugin which will make use of map tools but it
is giving me seg fault.
Operation is such : plugin has a pointer to qgsmaptoolzoom, on
activating action for this plugin it do

PointTool::PointTool(QgisApp * theQGisApp,
				       QgisIface * theQgisInterface):
                 QgisPlugin(sName,sDescription,sPluginVersion,sPluginType),
                 mQGisApp(theQGisApp),
                 mQGisIface(theQgisInterface)
{
	zoomTool=new QgsMapToolZoom(mQGisIface->getMapCanvas(),false);
}

void PointTool::okReceived()
{
	mQGisIface->getMapCanvas()->setMapTool(zoomTool);
	
}
this will make zoomTool current map tool.
Aftert this if i select tool identifyfeature, and again select
zoomTool from plugin menu it results in segmentation fault. I couldn't
find solution for this problem. please help me get out of it. The code
which i put up is i think only relevant here, rest is std generated by
plugin builder or i can put whole code.
quickNitin