Web Forms :: DropDownList Switches From Spanish Into English?

Why would a DropDownList switch from Spanish into English when one selects a new item in it? And how does one prevent that from happening?

[Code]....

When you first come to this page after having chosen Spanish as your language, the dropdown is populated with the ListItems texts displaying -- as expected -- in Spanish. But when you go to select another item from the dropdown, all the items come back in English!

When you examine the dropdown before the AutoPostBack (both server-side and in FireBug), each ListItem is properly set, as in

Value="Some English" Text="Some Español"
whereas **after** the PostBack, it looks like
Value="Some English" Text="The same English"

Why is this happening, and what can I do to get it to keep the Spanish one sees before any PostBacks?

**Notes**:

1. The routine pointed to in `OnSelectedIndexChanged` is currently commented out, so the problem is not there.

2. I added `EnableViewState="true"` to the DropDownList, but that didn't make any difference, so I removed it.

3. As suggested below by Ichiban, I moved setting the `Thread.CurrentThread.CurrentUICulture` from `Page_Load` to `Page_Init()`, but that too didn't make any difference.