Precisison T3500: Freeze on Startup (Network card issue?)

I have a problem with four Precision T3500 computers. All of them freeze at startup and when trying to log on.

The computers running Windows XP and I belive that the problmet is situated at the NIC, we can get around that the computer freezes when disconnecting the network cable at startup. We have about 40 other computers that works without problems on the network (and with the same setup) and all are different Dell computers (no other contrast T3500).

The computer freezes when "Applying Computer Settings"(I have used Google Translate for this, when the settings for the computer is set at startup) and it may take a long time (10 - 30 minutes) to log into the computer when loading personal settings (if you come past the first freeze). The personal settings loads network drives as units, etc.

I have tried to update the drivers from the original and there was a marginal improvement (works every other time with the network cable plugged in). I have been looking on the web where I found the only advice to update the drivers. What's wrong and how can I fix it?

(I tried sending a email but got an error message about that said it was not available right now)