We've got 5 Fujitsu E9900 DT7-D2924 that falls into boot-loop (the keep rebooting) after recent Windows XP updates.
They all run Windows XP SP3, and i expect one of the hotfixes installed within the last month to be the cause. A "system restore" that roll's back the updates fixes the problem, but I had to disable automatic updates to avoid the problem to reoccur.
The next step, is to manually install the 40+ hotfixes one by one, to see which one is casing problems. Very time consuming, so any hints are greatly appreciated..