When using Ubuntu 8.10 and connecting to a Wireless-n (802.11n) network, the system freezes with kernel panic (as indicated by blinking scroll and numlock). The system gets unusable and you would have to reboot. I have had this issue with my Dell XPS M1530, when connecting to Apple Extreme router.
The issue with the intel wireless module driver, and will get fixed by installing the compat-wireless driver.
Try compiling this iwlagn module, http://www.orbit-lab.org/kernel/compat-wireless-2.6/2008/10/compat-wireless-2008-10-01.tar.bz2 .
Extract the archive and then follow these steps:
sudo apt-get install build-essential cd compat* make sudo make install
Reboot the system, and you will not longer face kernel panic or system freeze.
When installing 9.04, I figured out that 802.11N drivers for Ubuntu are totally broken. Since I did not want to fiddle around much, I added the following lines to /etc/modprobe.d/options(and restart the system):
options iwlagn 11n_disable=1
This would prevent Wireless-N mode, but it will get your Dell M1530 (and M1330) working on Wireless with Ubuntu