Visual Studio 2010 bug - editor

I recently ra开发者_运维百科n into a strange behavior in the VS2010 SP1 IDE. When I modify an aspx page viewing the markup, I get duplication in nearby controls.

For example, I have a Dropdownlist control that looks like this:

 <asp:DropDownList ID="cboPreviousPhone" Width="350px" CssClass="EntryText"></asp:DropDownList>

Directly above it, I add table tags. When I add tr tags, the ID of the dropdown list changes to this:

<asp:DropDownList ID="cboPreviousPhor" Width="350px" CssClass="EntryText"></asp:DropDownList>

If I type "tr1234" in the tag instead, the dropdown changes to this:

 <asp:DropDownList ID="cboPreviousPhotr1234r" Width="350px" C`ssClass="EntryText">/asp:DropDownList>

I tried this project on another machine and get the same thing. Deleted designer file, same thing.

Any ideas why this would do this?