Browsing through my logs I see a ton of searches like this:
chrome setup.exe not valid win32
I’m not sure which part of this site they are hitting. Anyway, this is for you.
In my experience “not a valid win32 application” invariably means a corrupt executable. I’d guess that what has happened here is that your web browser did not download the entire setup file, but stopped half way. Internet Explorer is particularly bad in this respect: it tells you that a download is complete, when you can see that it is not because the download size is not what it should be. It usually happens when the connection is poor, either at your end, or because of a busy server. It beats me why browsers don’t make a basic check on the file size after download.
It can also happen with a CD or DVD install, if the disk is corrupt or the drive is failing; or if your hard drive is failing.
The usual solution is to re-download the file.