Services startup log?

Dear all,

for some time (do not know the exact time, so tracing back the culprit
service/process is impossible) some kind of service / process puts
explorer on a hold after I log in to my XP Prof. SP3 - latest patches.
Hovering the mouse over the taskbar results in a sandwatch icon and
the Start- button, quicklaunch etc. are disabled. The only way to get
some response is to ctrl-shift-esc into the task manager, kill
explorer.exe and restart it.

Using sysinternals' "autoruns"-tool reveals literally hundreds of
entries for services/processes to be started. The windows Eventlogs do
not show any errors.

So my question is: is there an application / service, that can
monitor / log _everything_ that is happening after the login so I
could try to find the item that blocks the further execution of
remaining auto-run processes and applications? I tried with a very
naive approach to kill processes from their highest PID downwards, to
no extend and I am not really happy with the prospect of disabling all
services, enabling them service-by-service, re-logon and see when the
hanging starts.

Thank you for any hints in advance
Cheers
Jakob