Created Unassigned: error locating ToolkitScriptManager [27579]

I am using c# 4.0 and I have a page with ModalPopUpExtender and HTMLEditorExtender
when the execution reaches the end of the Page_Load of the master page I get this error:

Locating source for 'f:\TeamCity\buildAgent\work\80acd78aa4c25314\Server\AjaxControlToolkit\ToolkitScriptManager\ToolkitScriptManager.cs'. Checksum: MD5 {da 88 3a 9f 11 fc 1f 88 7f 32 d6 44 ff a 4f b7}
The file 'f:\TeamCity\buildAgent\work\80acd78aa4c25314\Server\AjaxControlToolkit\ToolkitScriptManager\ToolkitScriptManager.cs' does not exist.
Looking in script documents for 'f:\TeamCity\buildAgent\work\80acd78aa4c25314\Server\AjaxControlToolkit\ToolkitScriptManager\ToolkitScriptManager.cs'...
Looking in the projects for 'f:\TeamCity\buildAgent\work\80acd78aa4c25314\Server\AjaxControlToolkit\ToolkitScriptManager\ToolkitScriptManager.cs'.
The file was not found in a project.
Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\crt\src\'...
Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\atlmfc\src\mfc\'...
Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\atlmfc\src\atl\'...
Looking in directory 'C:\Program Files\Microsoft Visual Studio 10.0\VC\atlmfc\include\'...
The debug source files settings for the active solution indicate that the debugger will not ask the user to find the file: f:\TeamCity\buildAgent\work\80acd78aa4c25314\Server\AjaxControlToolkit\ToolkitScriptManager\ToolkitScriptManager.cs.
The debugger could not locate the source file 'f:\TeamCity\buildAgent\work\80acd78aa4c25314\Server\AjaxControlToolkit\ToolkitScriptManager\ToolkitScriptManager.cs'.