We have an extension and installer that call IOpenService.setDefault() to set default search engine. We recently upgraded our code signing certificate, now with the upgraded cert, on 32 bit machines using IE9 and IE 10 the call to setDefault is failing (returns OS_E_CANCELLED immediately and no Search Provider Default dialog appears). The same binaries work fine with IE9/10/11 on 64 bit machines. That is we get the Search Provider dialog and our company name is verified.
Also we use an "unsigned" version of the binaries, the code works on 32-bit IE9/10, that is we get the Search Provider Default dialog but the company name is prefixed with (Not Verified)