It seems that the needed stylesheets or images for the grid are not present on the page in the problematic case. Generally, the purple color I see in the screenshots is not part of our built-in skins and I cannot speculate where it comes from or why is it missing in some cases.
If this happens only under IE, it is possible that your page has reached its stylesheet limitation
If you are changing the skins of the grid in the code-behind you would need to set its EnableAjaxSkinRendering property to true when you do that.
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