Thank you for the bug report.
To turn off keepalive, you should set "Max keepalive requests" to 0 or 1, either at server level or at vhost level. changing keepalive timeout will not work.
The setenvif trick in apache does not work with LSWS. And,we don't find any real problem with using SSL keepalive with IE, maybe it is a bug in somewhere else. Please let us know if the problem persist when keepalive has been turned off. If we can reproduce the bug, we will fix it.
New bugfix release will be available soon. stay tuned. :-)