Index: /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceUtils.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceUtils.cpp	(revision 23654)
+++ /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceUtils.cpp	(revision 23655)
@@ -37,4 +37,16 @@
 
 #ifdef VBOX_WITH_GUEST_PROPS
+/**
+ * Wrapper around VbglR3GuestPropWriteValue that does value formatting and
+ * logging.
+ *
+ * @returns VBox status code. Errors will be logged.
+ *
+ * @param   u32ClientId     The HGCM client ID for the guest property session.
+ * @param   pszName         The property name.
+ * @param   pszValueFormat  The property format string.  If this is NULL then
+ *                          the property will be removed.
+ * @param   ...             Format arguments.
+ */
 int VBoxServiceWritePropF(uint32_t u32ClientId, const char *pszName, const char *pszValueFormat, ...)
 {
@@ -42,4 +54,6 @@
     if (pszValueFormat != NULL)
     {
+        /** @todo Log the value as well? just copy the guts of
+         *        VbglR3GuestPropWriteValueV. */
         VBoxServiceVerbose(3, "Writing guest property \"%s\"\n", pszName);
         va_list va;
@@ -51,5 +65,9 @@
     }
     else
+    {
         rc = VbglR3GuestPropWriteValue(u32ClientId, pszName, NULL);
+        if (RT_FAILURE(rc))
+            VBoxServiceError("Error removing guest property \"%s\" (rc=%Rrc)\n", pszName, rc);
+    }
     return rc;
 }
Index: /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo-win.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo-win.cpp	(revision 23654)
+++ /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo-win.cpp	(revision 23655)
@@ -380,5 +380,5 @@
         {
             VBoxServiceError("Failed to query registry key (install directory)! Error: %Rrc\n", rc);
-        }    
+        }
         else
         {
@@ -401,7 +401,7 @@
 
     /* Write information to host. */
-    rc = VBoxServiceWritePropF(uiClientID, "/VirtualBox/GuestAdd/InstallDir", szInstDir);
-    rc = VBoxServiceWritePropF(uiClientID, "/VirtualBox/GuestAdd/Revision", szRev);
-    rc = VBoxServiceWritePropF(uiClientID, "/VirtualBox/GuestAdd/Version", szVer);
+    rc = VBoxServiceWritePropF(uiClientID, "/VirtualBox/GuestAdd/InstallDir", "%s", szInstDir);
+    rc = VBoxServiceWritePropF(uiClientID, "/VirtualBox/GuestAdd/Revision", "%s", szRev);
+    rc = VBoxServiceWritePropF(uiClientID, "/VirtualBox/GuestAdd/Version", "%s", szVer);
 
     if (NULL != hKey)
@@ -494,5 +494,5 @@
         rc = VBoxServiceGetFileVersionString(pTable->pszFilePath, pTable->pszFileName, szVer, sizeof(szVer));
         RTStrPrintf(szPropPath, sizeof(szPropPath), "/VirtualBox/GuestAdd/Components/%s", pTable->pszFileName);
-        rc = VBoxServiceWritePropF(uiClientID, szPropPath, szVer);
+        rc = VBoxServiceWritePropF(uiClientID, szPropPath, "%s", szVer);
         pTable++;
     }
Index: /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo.cpp	(revision 23654)
+++ /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo.cpp	(revision 23655)
@@ -159,14 +159,14 @@
     char szInfo[256] = {0};
     rc = RTSystemQueryOSInfo(RTSYSOSINFO_PRODUCT, szInfo, sizeof(szInfo));
-    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/Product", szInfo);
+    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/Product", "%s", szInfo);
 
     rc = RTSystemQueryOSInfo(RTSYSOSINFO_RELEASE, szInfo, sizeof(szInfo));
-    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/Release", szInfo);
+    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/Release", "%s", szInfo);
 
     rc = RTSystemQueryOSInfo(RTSYSOSINFO_VERSION, szInfo, sizeof(szInfo));
-    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/Version", szInfo);
+    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/Version", "%s", szInfo);
 
     rc = RTSystemQueryOSInfo(RTSYSOSINFO_SERVICE_PACK, szInfo, sizeof(szInfo));
-    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/ServicePack", szInfo);
+    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/ServicePack", "%s", szInfo);
 
     /* Retrieve version information about Guest Additions and installed files (components). */
@@ -176,9 +176,9 @@
 #else
     /* VBoxServiceGetAddsVersion !RT_OS_WINDOWS */
-    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestAdd/Version", VBOX_VERSION_STRING);
+    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestAdd/Version", "%s", VBOX_VERSION_STRING);
 
     char szRevision[32];
     RTStrPrintf(szRevision, sizeof(szRevision), "%u", VBOX_SVN_REV);
-    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestAdd/Revision", szRevision);
+    VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestAdd/Revision", "%s", szRevision);
 #endif
 
@@ -263,5 +263,8 @@
 #endif /* !RT_OS_WINDOWS */
 
-        VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/LoggedInUsersList", (uiUserCount > 0) ? szUserList : NULL);
+        if (uiUserCount > 0)
+            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/LoggedInUsersList", "%s", szUserList);
+        else
+            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/LoggedInUsersList", NULL);
         VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/OS/LoggedInUsers", "%u", uiUserCount);
         if (g_VMInfoLoggedInUsers != uiUserCount || g_VMInfoLoggedInUsers == UINT32_MAX)
@@ -331,5 +334,6 @@
         int iCurIface = 0;
 
-        VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/Net/Count", "%d", (nNumInterfaces > 1 ? nNumInterfaces-1 : 0));
+        VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, "/VirtualBox/GuestInfo/Net/Count", "%d",
+                              nNumInterfaces > 1 ? nNumInterfaces-1 : 0);
 
         /** @todo Use GetAdaptersInfo() and GetAdapterAddresses (IPv4 + IPv6) for more information. */
@@ -369,5 +373,5 @@
 #endif
             RTStrPrintf(szPropPath, sizeof(szPropPath), "/VirtualBox/GuestInfo/Net/%d/V4/Broadcast", iCurIface);
-            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, szPropPath, inet_ntoa(pAddress->sin_addr));
+            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, szPropPath, "%s", inet_ntoa(pAddress->sin_addr));
 
 #ifdef RT_OS_WINDOWS
@@ -387,13 +391,9 @@
 #endif
             RTStrPrintf(szPropPath, sizeof(szPropPath), "/VirtualBox/GuestInfo/Net/%d/V4/Netmask", iCurIface);
-            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, szPropPath, inet_ntoa(pAddress->sin_addr));
-
-             if (nFlags & IFF_UP)
-                RTStrPrintf(szTemp, sizeof(szTemp), "Up");
-            else
-                RTStrPrintf(szTemp, sizeof(szTemp), "Down");
+            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, szPropPath, "%s", inet_ntoa(pAddress->sin_addr));
 
             RTStrPrintf(szPropPath, sizeof(szPropPath), "/VirtualBox/GuestInfo/Net/%d/Status", iCurIface);
-            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, szPropPath, szTemp);
+            VBoxServiceWritePropF(g_VMInfoGuestPropSvcClientID, szPropPath,
+                                  nFlags & IFF_UP ? "Up" : "Down");
 
             iCurIface++;