Hi Philp47,
Welcome to Vista Forums.
I do not know how to repair this problem globally. It also occurs for some (actually, many) documents on my system where they are obviously more than 1 page - so it appears to be a Vista issue and/or possibly an Office/Word issue (assuming that's what you're using) and not one with your computer or settings (unless by chance I have the same problem or settings myself but that is doubtful). Some, however, do seem to work properly. I can't find a common pattern though it seems to work on newer files and not work so well on the older ones - but that's not absolute or consistent (there are exceptions to both "rules").
I do know how to fix it for a specific document (I just did it several times). Open the document and then save it. When you check Windows Explorer, that document will now show the proper number of pages. I imagine you don't particularly care to open all the 1-page documents to reset them this way - but it is a workaround for those you use frequently or if you really need this only on a smaller subset of documents. You can speed up this process slightly by opening multiple documents at the same time, saving each and then closing them - it isn't much of a difference but it may help. Here's how (just ignore the edit part and simply save the documents without editing and then close them):
How to Edit Multiple Word Documents | eHow.com.
I'll keep looking for a more global solution, but I'm not extremely hopeful.
One other thought. If you bulk convert the documents (perhaps from .doc to .docx or whatever), this will result in a newly saved document which may show up properly in Explorer (since it was just saved). But I don't know for sure if this will work (I'm essentially guessing and might try it on a couple to see what happens before doing them all). Furthermore, you may not want to convert your files (and I don't know of any program that converts from one type to exactly the same type and creates a new file in the process). Plus I don't know what type of documents you're talking about or what programs and versions you are using - and I'd need you to provide that information in your next post if you're interested in pursuing this option further. Again, I'm not at all certain this would work or would apply in your situation - it's a wild shot in the dark - but I'll do more research if you'll provide the additional information
and are willing to consider this whether or not it works.
I hope this helps (at least a little).
Good luck!