Win 7 Professional OS. I am fairly confident there were updates downloaded and installed on Thursday (night) night but the Win7 update log shows nothing. Regardless, yesterday (Fri) morn I powered up the 'puter, it seemed to boot, but then it crashed and I was greeted with the BSOD along with the error BAD_POOL_HEADER message. Googling for (helpful) information was inconclusive; it could be new hardware, new software, bad hardware or software, etc. Ultimately I was able to boot the 'puter and use it all day with no (visible) problems. This morning was a repeat except this time the error was PAGE_FAULT_IN_NON_PAGE_AREA. Googling for information is again not very helpful; it could be this, that or another thing. Once again the 'puter will boot after the initial boot, crash, warning and re-boot. I have not installed any new hardware or software. That said, a few days ago Win7 complained about one of the external drives I've had for months, but it seems fine now. Please do not suggest running "ix"; I have more than one version of "ix" available to me but I have software that runs only on Windows, hence I remain with Win despite the all too frequent problems. If necessary, I will reinstall Win7 and assume/hope the problem is not hardware related.