Downloaded IE9 on my laptop and my desktop. WordPress 3.2 dashboard works fine in both. Tested IE9 x86 and x64, both machines run Windows 7 x64.
If the problem is not with WordPress or your local machine, the only possibility is with your host/server.
1: Does the server use any page compression or caching, such as GZIP? Can you turn it off?
2: Are pages being server by an intermediary? I have seen Content Delivery Networks (CDN’s) cause issues with WordPress’ dashboard. Do you (or your host) use CloudFlare protection? There is a known issue between the two.
As much details as you can provide about your setup is all that will be helpful here.