I keep enabling comments on my pages, but Blogger keeps disabling them!
From having observed the reports of the problem, it appears to affect all blogs - both varying template type, and use of the different GUIs (Classic and New 2011), appear to be referenced.
Blogger Support has acknowledged the problem.
Thanks everyone for your patience, we're hoping to have a fix rolled out shortly.
(Update 10/19): This has been corrected.
(Update 11/09): Today, we see a new problem with static pages and comments - this one involving dynamic views.