GoogleUpdate.exe - broken on our corporate network

This is an odd one. I don't have the answer, so any hints would be much appreciated.

In our corporate environment when we try to install any Google Products we now get what I'm guessing is the GoogleUpdate.exe XML manifest instead. It starts like this (example, Chrome, emphases mine):

... <asmv1:assembly xsi:schemaLocation="urn:schemas-microsoft-com:asm.v1 assembly.adaptive.xsd" manifestVersion="1.0">
<assemblyIdentity name="Google Installer.app" version="1.2.133.37" publicKeyToken="9a8dfcd080ccb114" language="neutral" processorArchitecture="x86"/>
<description asmv2:publisher="Google, Inc." asmv2:product="Google Installer"/>
<deployment trustURLParameters="true" install="false"/>
−
<dependency>
−
<dependentAssembly dependencyType="install" codebase="clickonce_bootstrap.exe.manifest" size="13531">
<assemblyIdentity name="clickonce_bootstrap.exe" version="1.2.133.37" publicKeyToken="9a8dfcd080ccb114" language="neutral" processorArchitecture="x86" type="win32"/> ...

Chrome itself can still install Google Apps, but nothing else can.

We assume "Google Installer.app" is broken for us. This does not appear to be a common problem, though it's now universal in one company.

It's hard to get information on "Google Installer.app". I presume it's related to "GoogleUpdate.exe", but there are currently no pages that mention both (except this one). This is the best page I've found on GoogleUpdate.exe:

GoogleUpdate.exe - Google Chrome Help

GoogleUpdate.exe is a software component that acts as a meta-installer and auto-updater in many downloadable Google applications, including Google Chrome. It keeps your programs updated with the latest features. More importantly, GoogleUpdate allows your Google applications to be rapidly updated if security flaws are discovered...

I don't think this problem is a result of our corporate "webwasher" filters, because I think we can install will work when we connect to other networks.

Any ideas? (I tried Google's Help Groups, but they're continuing their record of being 100% useless for me.)

Update: From the Google Pack site we can install Chrome and GoogleUpdater.exe (also Earth, Picasa, etc). Chrome doesn't do one click installs of Google's products, so if you use Chrome to install a browser plug-in like Google Video Chat Google provides an executable (such as GoogleVoiceAndVideoSetup.exe) that's stored in the Downloads folder. This can then be run.