#PF—Page-Fault Exception (Vector 14) A #PF exception can occur during a memory access in any of the following situations: • A page-translation-table entry or physical page involved in translating the memory access is not present in physical memory. This is indicated by a cleared present bit (P=0) in the translation-table entry. • An attempt is made by the processor to load the instruction TLB with a translation for a nonexecutable page. • The memory access fails the paging-protection checks (user/supervisor, read/write, or both). • A reserved bit in one of the page-translation-table entries is set to 1. A #PF occurs for this reason only when CR4.PSE=1 or CR4.PAE=1. #PF cannot be disabled.