Lotus Notes r5 w/ XP Opening Error

We are running Notes r5 (5.0.08 and 5.0.11). The problem we are having is with Windows XP Pro. THe problem is slightly different depending on the version. In 5.0.08, if users are not members of the local admin group, when they attempt to open up Notes, they get a splash screen (Notes logo comes up and goes away), and are unable to run Notes. If they are admin, they can open up fine. In 5.0.11, non-admin users can open up Notes, but it will prompt to choose the user.id file (it is looking in thecorrect folder). They can choose th file and run, but the next time they open up Notes, they have to choose it again. I cannot find anything on their support page in regards to this. Help!!