The problem seems to be to do with the usb host controllers regarding suspending and resuming as temporarily editing
/proc/acpi/wakeup, as noted on Ubuntuforums, might sometimes enable successful suspending of the ASUS 1201N.
However, to implement a permanent solution you would probably need to create a custom suspend script or try the script from here. It has been said to work with the 1201N on that site and on this forum, but you just need to change
DRIVERS="ehci xhci" to DRIVERS="ehci ohci" in the body of the first script on the site. I've also posted the edited script from the site in a pastebin slot in case the original site becomes unavailable.
So, create a file such as this one (the title doesn't matter, but must be prefixed with at least 20 to override any other files):
sudo touch /etc/pm/sleep.d/20_custom_usb
and refer to the the pastebin copy of the script, which has the changed
DRIVERS section. Now open your new file and copy the contents of the script into it with:
sudo nano /etc/pm/sleep.d/20_custom_usb
Then make it executable with
sudo chmod 755 /etc/pm/sleep.d/20_custom_usb
You can then restart your machine and then test to see if it suspends correctly. This method has been said to work on that site, as the comments on the forums testify, and is definitely worth trying.
Other than that, it may be a bug with the kernel you are using, although that is unlikely. However, see this report at Launchpad. The only alternative there was to upgrade the kernel or take the risk of using one of the more recent mainline kernels. See this article for more on the dangers of using the mainline kernels: