I'm not sure the number reported by site: is something to go on.
I have one client site that has around 1500 pages, MSN says it sees 468.
I have another client site that has around 70 pages, MSN reports it as having 238 pages.
One of my personal sites has just over 500 pages, and MSN reports it as 1970 pages.
None of these sites is ranking as well as it was a couple of months ago; one has severely tanked in MSN (ironically at the same time it's risen quite high in Google and Yahoo)