I saw something similar. (Tho have "search engine friendly" URLs, but same priniciple I think.)
So, trying linking directly from menu on home page to main pages, in hopes that will minimise PR dilution. (Not sure if this is right or not; haven't checked much, esp with apparent uncertainties in PR displayed in toolbar.)
One the same site with a mix of plain html pages and dynamic ones, both pages are indexed, only the PR differs...Dynamic url example: www.mysite.com/scripts/ABCEContent.dll/ShowPage?PageName=wheretoeat. This page has a PR 0 while a static html page: www.mysite.com/wheretostay.htm has a PR 4.