in your online example, the html view looks like:
IE7 - <span style="COLOR: #33cccc">Type here</span>
FireFox - <span style="color: #33cccc;">Type here</span>
but after i hit submit it looks like:
IE7 - <span style="COLOR: &3cccc">Type here</span>
FireFox - <span style="color: &3cccc;">Type here</span>
my example demonstrates two different browsers delivering the same results, on three seperate machines.
ironically, we don't actually need to use EncodeHiddenValue anymore - residue code left over after debugging a preview page - but i thought i'd let you know of our experience as it caused untold worries!