After installing the update KB2870699 IE users get the message "The signature of this program is corrupt or invalid" when downloading MSI installation files. We have verified that removing the update resolves the problem and installing it causes the problem to recur.
The issue has been verified on Windows 2008 R2 SP1 and Windows 7 (SP unknown). It has also been verified that it occurs in IE9 and IE10.
The files and signatures being used for testing have been verified and are not invalid. Numerous MSI files built over the past twelve months have been tested.