hi there, thanks for any help I can use. Windows XP home sp2 motherboard : nvidia nforce4-a939 bios updated to 1.1k (latest) graphic card : nvidia 7950GT 1024 ram crucial (2x512) Trend Micro ionternet security I have nothing installed on the computer I have installed win on a different HD=> same pb I have reinstalled 10 time windows, and still the same problem. It quits when ever or reboot itself without warning.Even the safe mode is not working properly ! either it does not boot or after listing all the disabled drivers it reboots ! a real nightmare. My firefox quits most of any downloaded files, I get a message " file corruped" evey time win quits and reboots (when I can) got a box saying "windows ahas recovered from a serious issue" and if I click on the tech info : c:.....min052607-02.dmp and c:....sysdata.xml. when I install windows I got the blue sceen quite a few time : irql_not_less_or_equal or page_fault_in_nonpaged_area or pnf_list.... When I installed the nvidia driver from cd (provided) got : nforce4 pci express root port, has not passed the XP test....??? It is a real mess !I do not know what to do anymore. any idea !!! thanks again.