Windows XP Slow Domain Logon

Hi all,

Have a funny scenario with some of the XP Pro systems on our domain. We have twenty HP systems in our lab and joined to our domain. When a user logons on there is about a 2 minute delay before they reach their desktop. It hasn't been a huge problem and I just assumed that it was system specific [suffice it to say HP isn't building their Compaq business line the way Compaq did].

Anyway, we recently had to replace four of the systems [believe it or not we have already lost 1/4 of our systems in the first year, likely due to cheap motherboards]. Here's where the confusion starts. On the year-old systems we get the above cited phenomenon. On the newer systems the logon is a normally timed logon between pressing enter and reaching the desktop. The systems are virtually identical HP systems. So I'm left wondering, "What gives?" Why would it take so long for the first set of systems to reach their desktops, when it obviously isn't a network wide issue? Any advice is appreciated.