Uninstalled, left the sync folders, try installing 3.8, and it tells me I need to uninstall the newer version I have. I have already uninstalled it, it's not listed in add/remove programs anymore. What a headache. Any clue how to get 4.0 off the system so 3.8 can go back on?

Tried deleting RAPI.DLL also, but the file is removed automatically when i uninstall the program. No matter how many times i installed/uninstall 4.0, still says its on my system, and wont let me install 3.8

Have you trawled through the registry for A/S 4.0 entries? (Don't forget to back up your registry before playing whith it, though, just in case!)

You can get a Registry Editor for free from here (but please note the author's PayPal button on the right for donations!):

http://www.phm.lu/Products/PocketPC/