We have about 15 Dell Precision 650's in our organisation (Duel Xeon Core)
however all 15 of these machines have had issues since we upgraded to the
latest 490 SP2 client.

The client itself contains ALL updates released on with the exception of
the new NWGINA.

When the machines get build they get installed with an older version of the
client, currently 4.90 SP2 without any extra patches and this works fine,
as soon as the machines take the new upgrade, via the login script and
ACU.EXE the machines reboot when you press CTRL+ALT+DELETE! They will do
this for an unspecified amount of time however it wont reboot and the user
will be able to login. The issue is that this amount of time can be as long
as an hour before the user can login which doesnt help matters!

Any help appreciated as I am really at a loss as to what is casusing this
issue and I am reluctant to roll out to our other 1500 machines until I
know what is causing this issue on our duel core boxes.