Index: branches/RC/core/install.php
===================================================================
diff -u -r11121 -r11168
--- branches/RC/core/install.php	(.../install.php)	(revision 11121)
+++ branches/RC/core/install.php	(.../install.php)	(revision 11168)
@@ -448,6 +448,11 @@
 						$this->errorMessage = 'Please select module(-s) to ' . ($this->currentStep == 'choose_modules' ? 'install' : 'upgrade');
 					}
 
+					if ($this->currentStep == 'choose_modules') {
+						// don't check interface modules during install, only for during upgrade
+						break;
+					}
+
 					// check interface modules
 					$available_modules = $selected_modules = Array ();
 					$interface_modules = Array ('Core', 'Proj-Base');