[QT Maya2013] Signal issues

Has anyone else encountered crash bugs when processing widget signals in Maya?
I’m struggling to get a handle on exactly why this is happening. For example:

self.lineEdit.textChanged.connect(self.inputProxyModel.setFilterRegExp)		#works
self.lineEdit.textChanged.connect(self.Foo)					#crashes

self.pushButton.clicked.connect(self.Bar)					#works
self.pushButton.connect(self.pushButton, QtCore.SIGNAL(‘clicked()’), self.Bar)	#crashes

self.treeView.setContextMenuPolicy(QtCore.Qt.CustomContextMenu)
# Subclassing QTreeView and defining context menu there				#works
self.treeView.customContextMenuRequested.connect(self.contextMenu)		#crashes

Thx.
S.

Resolved.
Cause was internal heap corruption issue in version of PyQt4 we were running.
Updating to 4.9.1 got rid of these problems.