There was a bug when using the classic Timer with Google Chrome. It has now been fixed. If you are using Chrome please refresh your browser, just in case.
Namely, task stopping did not work. You could start a task nicely but when you tried to stop it, it would show like it did stop but in reality it kept running in the background.
The bug was not present with other browsers or the Widget.
We are sorry for the inconveniences this bug might have caused you.
The Toggl Team