Dear All:With this freeware program you can assign your computer tasks to use core 0 and then you can assign cores 0 and 1 to FSX or you can assign core 0 and 1 to FSX and then you can assign core 1 to the others tasks.Link:Set AffinityAlfredo Mendiola LoyolaLima, Per

excellent tools , i have been using them for few years now, just had to get latest version as i upgraded to win7.Many thanks to those who make such simple and excellent tool , and make it free.On my system fsx affinity mask is set to 14 = 1110 , which means fsx uses all but core 0.then i use affinity tool to set all addons+other some other stuff (eg ASA, fscommander rc4 etc ) to use core 0. Once set , it fixed even after reboot.I use only prifinitty , cause it also allows you to set priority, not just affinity.