Comment 65 for bug 577916

replacing the uuid in /etc/initramfs-tools/conf.d/resume
with the actual swap partition uuid fixed my problem

maybe that happened because I've had 9.10 with 10.04 and then I removed 9.10 and it seems that the swap was not enabled on Lucid and I enabled it manually. I don't remember what happened exactly but I usually told the second system to use the same swap of the first one.