Many people, myself included, have seen this dreaded error text:

<big><font color=red><UL><LI>Windows XP could not start because the following file is missing or corrupt: WINDOWSSYSTEM32CONFIGSYSTEM</big>
<LI><big>Stop: c0000218 {Registry File Failure} The registry cannot load the hive (file): SystemRootSystem32ConfigSOFTWARE or its log or alternate</font color=red></big>[/list]Microsoft knows about it. I'd like to see it a little less than I have, but if it happens....<UL><LI>How to Recover from a Corrupted Registry that Prevents Windows XP from Starting (Q307545)[/list]I espied this just after posting, as well - a hotfix. Don't just run out and apply this, folks, let someone glutton for punishment like me be a guinea pig.<UL><LI>Damaged Registry Repair and Recovery in Windows XP(Q318159)[/list]Bookmark the this link. You never know. And also think about installing the Recovery Console.