Index: umc/python/setup/util.py
===================================================================
--- umc/python/setup/util.py	(Revision 41790)
+++ umc/python/setup/util.py	(Arbeitskopie)
@@ -577,15 +577,19 @@
 
 	return pkglist
 
-def get_installed_packages():
-	'''Returns a list of all installed packages on the system.'''
-	cache = apt.Cache()
-	return [ p.name for p in cache if p.is_installed ]
-
 def get_installed_components():
 	'''Returns a list of components that are currently fully installed on the system.'''
-	allPackages = set(get_installed_packages())
+	# get all component packages that are installed
 	allComponents = get_components()
+	cache = apt.Cache()
+	allPackages = set([
+		ipackage
+		for icomp in allComponents
+		for ipackage in icomp['Packages']
+		if cache[ipackage].is_installed
+	])
+
+	# return installed components
 	return [ icomp for icomp in allComponents if not len(set(icomp['Packages']) - allPackages) ]
 
 # from univention-installer/installer/modules/70_net.py