Whenever someone brings a layout issue to your attention regarding Internet Explorer the first, almost instinctual, conclusion you come to is that it must be a CSS bug in IE's rendering. Usually it is. A few Google searches later and you've found someone who's diagnosed the issue, you implement the fix and you're good to go.
However, what happens when it's not Internet Explorer's fault?
This is what happened to us recently when we had a user bring to our attention a specific issue that we'd never seen before. Take a look at this screenshot. At first glance it looks as if there may be a layout issue, involving CSS, pushing the image down. The rub there is that this is an isolated instance of a problem with IE7. All of our computers with IE7 were fine and this was the first report of anything like this we'd seen with IE7, so there had to be something going on with this specific user's computer.
Where to look next? After some more inspection we noticed, as you will now, that all of the images in the page seemed a bit pixelated and even a bit bigger than they should be. We have had a few issues with users having their DPI set to 120 before and that causes font sizing issues. Could there be a correlating image sizing issue with IE?
After much sleuthing, Niki found a blog entry that details the exact issue we were dealing with. Apparently, when someone has a pretty nice monitor with a large resolution Windows has a registry value called UseHR that automatically upsizes the images to make it easier to see the images. In turn, this mungs up some Web designs. Here's the fix courtesy of Zieak's Blog.
1. Close Internet Explorer and click “Start”.
2. Select “Run” and type in “regedit” without the quotes.
3. In the left hand column click on the plus sign next to “HKEY_CURRENT_USER”.
4. Do the same for Software, Microsoft, and Internet Explorer.
5. Click on “Main” and scroll down on the right side of the window to “UseHR”.
6. Right click on “UseHR” and select “Modify” then change the “value data” to a zero instead of a one.
7. Restart IE and enjoy the non-jagged, newly smoothed web!
Presto! This worked like a charm for our user, however he still had the aforementioned DPI issue, which can be fixed by going to Control Panel >> Display >> Settings and clicking the Advanced button. Change the DPI back to 96, Apply, and Restart.
Talk about a bug out of left-field.
Yeah, this really highlights one of the key issues with web design - all the unknowns on the client side. Did you consider any server-side solutions, i.e. so that you don’t have to depend on the user contacting you with the issue, but in fact never experiences the problem?