XP slow to login to Win2K domain

On two different networks I have seen XP Pro take an extremely long time to load the user profile and apply security settings to an otherwise fast PC. The first network consists of one server and two clients. The second consists of three servers and40 clients. In each case, the XP Pro clients take a minimum of five minutes to get logged on. Win2K and NTWS clients have no such problems. Has anyone experienced (and hopefully fixed) this?