I have a real-time app that runs on a P4. The box we are running it on has an Aopen i865PEa-7IF motherboard. We are using the On-Time RTOS. We have found that every 37 seconds the app completely stops running for 250 microseconds. Using a PCI bus analyzer we discovered that between the last operation done by my app and when my app resumes running shows 100's and 100's of I/O reads and writes to addresses B3, EB, and 61. Googling on this has led me to believe that these accesses are related to SMI's and SMM. I have disabled everything in the BIOS - USB, LAN, power management, serial and parallel ports, modem, firewire, MIDI and game ports - yet my app still stops and I still see these accesses. Does anyone know how I can totally disable the SMI's? TIA! -larry