Since I’ve run into this issue myself, I thought I’d share a blog post that offers several possible workarounds while the ASP.NET team is looking at the issue:
If you are using the ASP.NET Menu control, you might encounter under certain circumstances an issue where the menu appears as a white box in IE8 Standards Mode.
What IE8 is doing IS correct (by design), in the sense that in Standards mode IE8 is following the standards. Specifically, (element).currentStyle.zIndex returns "auto" in Standards mode when zindex has not been set. The ASP.NET Menu control assumes a different value.
I’d like to suggest a few possible workarounds to solve quickly the issue (note, you can use either one of them, depending on your scenario):
- Overriding the z-index property
- Using CSS Friendly Control Adapters
- Adding the IE7 META tag to the website
Read the whole post for the details on the workarounds.