Did you ever wonder why the "integrated browser" of the Lotus Notes client behaves so differently compared to your regular browser? Here's one reason for that:
Using the "integrated browser"-option (on a Windows-OS) means that Lotus Notes utilizes the already installed Internet Explorer engine of your operating system to download and render web-pages (and also images in emails that need to be downloaded before you're able to see them). I would usually expect that engine to behave more or less the same way as the corresponding "standalone-browser", but that would be way too easy, right...?! ;-)
As soon as you have a situation where the user-agent-string of your browser matters, you're probably going to run into the same trouble which i encountered. You'll see that although you've already installed Internet Explorer 8 or even 9, the user-agent-string that the "integrated browser" transfers to the webserver, doesn't seem to fit into that picture. That's because the integrated browser is using the IE WebBrowserControl, which defaults to use an IE7-compatibility-mode that was introduced with IE8!
If you want to change that behaviour, you'll have to modify the registry like that:
I'm not sure if all of these entries are needed, but at least for the IEOOP.exe, i can confirm that this is used as soon as you open a webpage from within the Lotus Notes client.
(Some of) The remaining entries are needed if you don't want the engine to use the compatibility-mode for received mails where embedded images are downloaded from external resources (e.g. when you click "Show Images").