We are having problems with the last 2-3 versions of Contact Form 7 with users trying to submit forms in IE. They hang and do not send. No problems with Firefox or Chrome - but the problem exists with all versions of IE. We have a number of WP sites. The ones we have not recently updated to the latest versions of Contact 7 have no problem, but the one site we have updated experiences this problem. Even the recent update to 3.7.1 does not fix the problem. I hope this gets fixed, we are losing business over this problem!