Yep, know all about System Restore. . .I tried that too--it helped for about a day!
Something seems to be overriding the "normal" template. I figured out that all I need do is change the view to 100%--somehow it keeps changing the page view and size of the view--it sometimes just pops up as a "page preview" type layout with the smaller sizing. This is on a new document. Then I had issues with adding page numbers the other days--that was gray and couldn't be added. I found that if I changed the layout view and the view size--the page numbers were accessible again.
I've been having problems with things not printing properly from Word too. Everything shows up perfectly in print preview and on the document BUT when it prints a line skips in the printing. It could be anywhere in the document, sometimes more than one line. Check the formatting and everything is fine--maybe two or three prints the line of text will be there, the first or fourth it won't. Then I've had Word just crash itself in the middle of preparing a document--nothing else open, just Word. . .most of the time it saves or recovers the document, once it did not and there was major work involved!
All of these issues do "report" to MS when they happen, except the template changing thing--that's just got me stymied. So far, I'm just finding XP very unreliable as an OS.