Sometimes you need an entry with no time on it, for example to record a note against a task without adding hours. Avaza saves entries with a 0:00 duration, but not straight from the New timesheet entry popup: there, a duration of 0 starts a timer.
Use one of these two ways instead.
In Week view
Open Timesheets and click Week. Find the row, or click Add Row to add one.
Type 0 in the day's cell. It shows as 0:00 or 0.00, depending on your account's display format.
Add a note in the Notes box below the grid if you want one, and click Save.

See entering time for a whole week.
By editing an entry
Create the entry. Either click Start at the top of the page and stop the timer straight away, or add an entry in Day view with any duration.
Stopping the timer from the top of the page opens the Edit timesheet entry popup. For an entry you added, click its edit button in Day view.
Choose the Project and Category if they're empty, type 0 as the duration and click Save.

A timer you stop at once still holds a few seconds, which is why you change it to 0.
If the project requires notes on timesheets, add a note before you save. A zero-hour entry is otherwise like any other: it follows the project's approval rules, and you submit it with the rest of your time. See how timers work and getting started with timesheets.