cannot image Toshiba Satellite Pro laptop

We have a problem when we try to put an image on a Toshiba Satellite Pro
L20 laptop. The laptop boots normally from our Imaging server but after
entering the Zenworks Maintenance mode it hangs on the screen "Sending
DHCP request...". This is strange because we have 28 Toshiba laptops and
they were succesfully imaged earlier this year, when we were still using
Zenworks 4.01. We recently upgraded to Zenworks 7 SP1 and now it doesn't
work anymore. I also tried using a PXE-bootdisk but the result is the
same. I also tried to adjust the ZISD-area and changed DHCP to using a
static IP-adress, but this also doesn't work. Perhaps something has
changed in the Linux kernel, which causes the problem. The "Sending DHCP
request..."-screen mentions we are using Linuxrc v1.6 Kernel 2.6.5-7.244-
default.

Does anyone has a clue what's wrong?