Bah, I just realized I've been saying "Cloud GPS" while meaning to say "Marble" in my last few posts. With CSSU's forced rotation Navit works fine in portrait btw, it just needs a bit of .xml tweeks to have the layout realign a bit (but all the buttons are still visible).

Anyway, skykooler, I just got around to reinstalling Navit since my reflash, and the drawing a blank screen thing may have to do with it not auto-aligning to your position, even after it finds it. Just going to the menu, pressing Actions, selecting your position, and then the option that takes you there puts the map where you are. (Alternatively if you're unable to get signal, have it align to a city within the maps you've downloaded.)

9000: there's a thread called "Navit on N900" or something like that.

Read backwards from thr last page and you'll stumble upon a script a few pages in to download that will install the "latest" Navit for you. It's actually no longer the latest, so if you want the latest version you have to modify the names of the .deb files in that script accordingly, but if you can't figure out how to do that from the thread, you can just use it as is and get the almost latest version.