The procedure to hard reset the i730 has changed in the Windows Mobile 5 version (only). The new procedure is:

1. Press and hold down the top left menu button while pressing the slider down.
2. While performing the above, press the reset button located on the bottom left of the phone.
You will see a message "Formatting Root" let the process run without disturbing the phone.

It is a little tricky performing all three at once but it works.