Index: /trunk/src/VBox/NetworkServices/NAT/pxtcp.c
===================================================================
--- /trunk/src/VBox/NetworkServices/NAT/pxtcp.c	(revision 52007)
+++ /trunk/src/VBox/NetworkServices/NAT/pxtcp.c	(revision 52008)
@@ -1763,5 +1763,5 @@
         lim = sz - 1;           /* empty slot at the end */
     }
-    else if (lim == 1) {
+    else if (lim == 1 && beg != 0) {
         lim = sz;               /* empty slot at the beginning */
     }