After saving, Windows 7 reports "The signature of iview441_x64_setup.exe is corrupt or invalid." Tried Irfan View from several download sites, Plugins from one (Fosshub) all with same result. 32-bit versions generated no error.

It may be related to an error reported at, although kb2870699 is pretty old, and this bug is supposedly fixed in IE11:

"IE download with signature corrupt or invalid message and Microsoft KB2870699
Microsoft recently released security update KB2870699.

"Unfortunately this security patch broke code signing verification for all software developers who sign their executables using Starfield Certificate Authority (aka GoDaddy). The problem manifests itself when downloading a signed executable from Internet Explorer and then running it [or saving it?-mfa], and there maybe other ways this problem manifested itself (such as when launching our online backup client)."