I had the same problem with my acer. After changing MODULES="" to MODULES="ehci_hcd uhci_hcd" in /etc/default/acpi-support sleep and hibernate are working perfectly.
I had the same problem with my acer. After changing acpi-support sleep and hibernate are working perfectly.
MODULES=""
to
MODULES="ehci_hcd uhci_hcd"
in /etc/default/