If you are using a Nvidia card and have updated to the latest driver then that is most likely the problem.
I have just come in after leaving the pc updating all afternoon . Rebooted and tried suspend to ram and it will not resume.
I had the same problem on Chakra, so had to downgrade. Will look at possibilities tomorrow.
Asus M4A79XTD EVO motherboard, AMD Phenom II X4 965 CPU, 4 GB ram.
Gigabyte NVIDIA 9800GT Silent graphics card, Dell FP2007 22 Digital Flat panel.
Samsung harddisks 2 x 200gb SP2004S,1 x Hitachi 750gb HDT 72107,Optiarc SATA DVD-RW. Sabayon 64 & 32bit.