I've seen similar behavior (Lenovo T510, i5 ,using IGP graphics) when going to hibernate (not suspend). Suspend puts CPU & peripherals to sleep but memory is active/refresh. Hibernate writes the system state to disk(swap) and shuts down.
Please use the pull-down menu System=>Shutdown= select "Suspend" vs "Hibernate" and see which one is the problem.
If the problem w/ continuing disk activity is "Hibernate", then I've found that switching to a 2.3.37 kernel fixed the problem.
Perhaps selecting a 2.6.36 koji kernel would too. It'sa easy to try.