Could be a corrupted user profile, try on a new user account, or a group policy setting.
To add on MarcP's reply, you can verify this by starting Windows Vista in a clean boot mode. This will stop your programs/services from starting. See the link here for the steps on how to perform a clean boot: http://support.microsoft.com/kb/929135/en-usSomething is re-creating this folder when you boot up. I'd look at all the softwares you have that are set to start with Windows. One of them is causing this.