The Instruction At 0x72f151d3 Referenced Memory At 0x72f151d3. The Memory Could Not Be Written

Win 7 x64, all updates. intel core 2 duo E8800. 8gb ram in 2 pairs. Nvidia 9800GT.2x HDD with lots of free space. ESET antivirus + Outpost firewall Every time I shut down the computer, I get an error like this:The instruction at 0x72f151d3 referenced memory at 0x72f151d3. The memory could not be written.Sometimes they will auto close, others I will have to force the shutdown.The thing that seems interesting is that there's a pattern to the memory addresses.When it's a software exe crashing, it's always 0x7xxx51d3.When it's explorer.exe crashing, it's always 0x7xxx87bc.