Index: /trunk/src/VBox/Main/src-server/MachineImpl.cpp
===================================================================
--- /trunk/src/VBox/Main/src-server/MachineImpl.cpp	(revision 55834)
+++ /trunk/src/VBox/Main/src-server/MachineImpl.cpp	(revision 55835)
@@ -9068,4 +9068,6 @@
 
 #ifdef VBOX_WITH_GUEST_PROPS
+        /* Guest properties (optional) */
+
         /* Only load transient guest properties for configs which have saved
          * state, because there shouldn't be any for powered off VMs. The same
@@ -9074,8 +9076,13 @@
          * Note: can't rely on the machine state, as it isn't set yet. */
         bool fSkipTransientGuestProperties = mSSData->strStateFilePath.isEmpty();
-        /* Guest properties (optional) */
-        for (settings::GuestPropertiesList::const_iterator it = data.llGuestProperties.begin();
-            it != data.llGuestProperties.end();
-            ++it)
+        /* apologies for the hacky unconst() usage, but this needs hacking
+         * actually inconsistent settings into consistency, otherwise there
+         * will be some corner cases where the inconsistency survives
+         * surprisingly long without getting fixed, especially for snapshots
+         * as there are no config changes. */
+        settings::GuestPropertiesList &llGuestProperties = unconst(data.llGuestProperties);
+        for (settings::GuestPropertiesList::iterator it = llGuestProperties.begin();
+            it != llGuestProperties.end();
+            /*nothing*/)
         {
             const settings::GuestProperty &prop = *it;
@@ -9085,7 +9092,11 @@
                 && (   fFlags & guestProp::TRANSIENT
                     || fFlags & guestProp::TRANSRESET))
+            {
+                it = llGuestProperties.erase(it);
                 continue;
+            }
             HWData::GuestProperty property = { prop.strValue, (LONG64) prop.timestamp, fFlags };
             mHWData->mGuestProperties[prop.strName] = property;
+            ++it;
         }