We have a new Citrix XenApp 6.5 installation. Our HP t510 thin clients display two additional buttons in the task bar when IE9 starts. When an additional tab is opened, another two buttons appear.
The user cannot close the additional buttons.
The extra buttons only display when IE9 is opened. x64 or 32-bit versions of IE9 behave the same way. Non-thin clients do not have this problem.
This one is on HP, and if you hit this bug you'll have to contact HP support for the patch. Here's the good news -- you don't have to suffer hours of HP support.