What operating system exactly are you seeing this on? You've posted this in the Linux group, but I've only ever seen this happen on Mac. On Mac, you sometimes need to flip between windows with CMD+Tab to get the Fiddler window to appear (due to a bug in Mono on that platform). You might try killing the task using the Activity Monitor and restarting it.
oh thanks i got it open and i am on a mac
but now whenever i open it up it crashed halfway between displaying the update screen.
it also adds a proxy to chrome which means i have to deactivate it to go online, will this effect anything?