Last week we received quite a number of reports that the patch for MS10-015 was causing XP machines to display the dreaded BSOD (http://isc.sans.org/diary.html?storyid=8209).  The comments of that diary already suggested that the BSOD may have been related to a rootkit on the machine and it looks like this was correct.  If you were infected with the TDL3/TDSS/tidserv AKA Alureon rootkit  and applied the patch, then you would get the BSOD as the patch changed some pointers and the malware now tried to execute an invalid instruction.  

Lucky for us the malware writers have addressed this issue and it shouldn't happen again for those who are newly infected with this particular piece of malware.  A shame really, as  it was a convenient way in which to identify infected machines. If you did get the BSOD on your machine or on machines in your organisation, then you should consider the possibility that the machines are infected.

Marco's page (http://www.prevx.com/blog/143/BSOD-after-MS-TDL-authors-apologize.html ) and the Microsoft page (http://blogs.technet.com/mmpc/archive/2010/02/17/restart-issues-on-an-alureon-infected-machine-after-ms10-015-is-applied.aspx) go into the details.

Mark