For the last several weeks, I have not been able to comment on blogspot blogs because of some sort of bug in the system. Google doesn't seem to be doing anything permanent about it but, in case you are experiencing the same problem, I thought I'd share with you a couple of solutions. (BTW, this only seems to be affecting those using Internet Explorer.)
1. Log out of your Google account and then log back in without checking the "stay signed in" box. Annoying solution for me as I never log off my Google account.
2. Use a different browser. I've been working as a web designer the last several months and so I have several browsers installed on my computer for testing purposes. I tested the problem in Google Chrome and in Safari and both work fine. I'm sure others will as well.
Hopefully one of those things will work for now and hopefully Google is trying to come up with a solution to this problem (although I, personally, am not holding my breath).