I recently have not been able to vote on listings and comments and thought I may have been blocked..??
I then remembered that I had turned on Tracking Protection in IE9 recently so turned it off and voting worked again.
Worth checking if anyone is being blocked from voting for reasons other than a penalty.
Gotta admit that I have not used Internet Explorer for a while :) Just gave it a try and looks like we've got a few visual disparity to fix (comparing to other browsers).
However I did enable Tracking Protection and I can still vote. What are your tracking protection settings? Which ones you won't allow?
Do not that we use some Javascript libraries hosted on Google's servers (jQuery mostly), and if that gets blocked, many functions won't work.