Comment 140 for bug 305301

Though I haven't been running Ubuntu in a long time, I've experienced this issue with Debian Squeeze. I've been constantly tracking this ubuntu bug for a workaround.
Fortunately I've found a fix that is working pretty well for me.

Go to System Tools > Configuration Editor
Now browse to: apps/gnome-power-manager/general/network_sleep
Enable network_sleep by checking the box.

Now try to suspend/hibernate!

My specs are:

Laptop: HP Pavilion dv5035nr
Video card: ATI Tecnologies Inc Radeon Xpress 200M 5955 (PCIE)
Kernel: 2.6.32-4 (basically 2.6.32.9 upstream with NO backported DRM from 2.6.33)
Radeon driver: 6.12.6 (No KMS capable!)

What strikes me the most about this, is that it works with DRI enabled and user modesetting (no KMS needed). I haven't tried this with KMS enabled. I will try it once Squeeze gets its 2.6.32-10 kernel (with DRM backported from 2.6.33) and the KMS capable radeon driver 6.12.192 or 6.13.0

I got the fix from: http://bbs.archlinux.org/viewtopic.php?pid=705928

Hope this solves this bug once and for all!