During test with chrome, the extension sometimes crashes down…
WPT Chrome extension has crashed. Click this ballon to reload the extension. (See attachment)
The Chrome version is 23… I searched internet, but none found… Is there any clue here?
What version of wpt are you running (binary version information for wptdriver.exe or wpthook.dll)? You can get the latest here: https://sites.google.com/a/webpagetest.org/docs/private-instances#TOC-Updating-Test-Agents
That said, Chrome 23 is relatively ancient. Chrome is currently on version 29 for Stable so 23 is from almost a year ago. You might want to update your Browsers as well.