Index: /trunk/src/VBox/VMM/HWACCM.cpp
===================================================================
--- /trunk/src/VBox/VMM/HWACCM.cpp	(revision 22634)
+++ /trunk/src/VBox/VMM/HWACCM.cpp	(revision 22635)
@@ -648,4 +648,8 @@
             LogRel(("HWACCM: The host kernel does not support VT-x!\n"));
 #endif
+            if (pVM->cCPUs > 1)
+                return rc;
+
+            /* silently fall back to raw mode */
             return VINF_SUCCESS;
         }
Index: /trunk/src/VBox/VMM/VM.cpp
===================================================================
--- /trunk/src/VBox/VMM/VM.cpp	(revision 22634)
+++ /trunk/src/VBox/VMM/VM.cpp	(revision 22635)
@@ -295,8 +295,22 @@
 #endif
 
+                case VERR_RAW_MODE_INVALID_SMP:
+                    pszError = N_("VT-x/AMD-V is either not available on your host or disabled. "
+                                  "VirtualBox requires this hardware extension to emulate more than one "
+                                  "guest CPU.");
+                    break;
+
                 case VERR_SUPDRV_KERNEL_TOO_OLD_FOR_VTX:
-                    pszError = N_("The host Linux kernel is too old to support hardware acceleration. "
-                                  "Either upgrade your host kernel to Linux 2.6.13 or later or "
-                                  "disable hardware acceleration in the VM settings");
+#ifdef RT_OS_LINUX
+                    pszError = N_("Because the host kernel is too old, VirtualBox cannot enable the VT-x "
+                                  "extension. Either upgrade your kernel to Linux 2.6.13 or later or disable "
+                                  "the VT-x extension in the VM settings. Note that without VT-x you have "
+                                  "to reduce the number of guest CPUs to one");
+#else
+                    pszError = N_("Because the host kernel is too old, VirtualBox cannot enable the VT-x "
+                                  "extension. Either upgrade your kernel or disable the VT-x extension in the "
+                                  "VM settings. Note that without VT-x you have to reduce the number of guest "
+                                  "CPUs to one");
+#endif
                     break;