More details, please. Are you using http://cs.elderscrolls.com/constwiki/index.php/Windows_Vista http://www.gamesas.com/index.php?/topic/1088994-tescs-crashes-every-time-i-try-to-save/
I am using windows vista, i have tryed it with just loading the oblivione.esp and with oblivion.esp nights.est and dclshiveringisles.esp and i still can not save a new mod with out the CS crashing.