My P1i cannot be start again. after i start my phone and it restart by itself. And I need my contacts in that phone

USB ports supply very low voltage and may possibly go bad on the PC itself. Does the unit charge on a typical wall outlet plug? If not, then the DC jack on the phone itself is bad. Repairing this may be more costly that just buying a new phone.

format the phone

VERY SIMPLE JUST RESTART OR CHANGE ANOTHER LOGO TO AVOID THIS. AGAIN THERE IS ANY PROBLEM MEANS JUST REMOVE ALL CONTENTS IN MOBILE AND MAKE A BACK UP OF CONTACTS. THEN RESET THE PHONE. THIS **** WILL HELP YOU SIR .. THANK YOU

I ended up using SEUS and the phone is working fine now. (Sony Ericsson Uptate Service) But you need to copy your importand files from the phone before you start uptate ;D

You can try manual format & reset. It will delete EVERYTHING on the device, but will not harm your SIM or contacts. Remove any memory cards before doing this. Shut the phone off, and hold down both the top part of the circle pad(the spinning one) and the power button at the same time
or:
flash new software install in the phone problem will solved quickly

Go to settings and turn off automatic updates.

The only thing to do is go to your network shop, explain the situation and that you would like to try a different charger.
If you`ve checked battery and charger then it would be the phone itself.
If you are in warranty claim a new phone.

try formatting the phone

yes,it's a major problem with uiq phones they need to be ''restarted'' once a day, also try switching off 3g if you don't use it and if you don't have good 3g coverage.

Solution Description:

1. Log on to: http://www.sonyericsson.com/cws/support/softwaredownloads/p1i?cc=hk&lc=en
2. Download and install Update Service on your computer to keep the software in your phone up-to-date and ensure optimum performance from your phone.
3. When the download is complete, an Update Service shortcut will be created on your desktop.
4. While still connected to the Internet, click the ‘Update Service’ shortcut icon on your desktop
5. Sony Ericsson window will pop up and downloading will begin. Allow the downloading to run complete to 100%
6. Another Sony Ericsson window showing different countries’ languages will pop up, select your preferred language.
7. Sony Ericsson ‘Welcome to Update Service’ window will pop up, showing ‘Exit’ on the left-hand side and ‘Start’ on the right-hand side.
8. Click the ‘Start’ icon and select ‘Agree’ on the ‘Term of Use’ page that pops up
9. Select your phone type and click on ‘Continue’
10. Highlight your specific phone type and select ‘Continue’
11. Follow the instructions as shown below:

- Make sure your phone is fully charged
- Connect the USB cable to a USB port on your computer
- Turn off your phone
- Remove and reinsert the battery
- Press and hold the ‘C’ button down while plugging the USB cable to the computer
- Continue to hold the ‘C’ button down until the instruction number ‘7’ on the Update Service comes up (i.e. Instructing you to ‘Release the ‘C’ button)

1. Allow the update to run to the end
2. When the system informs you that the latest update has already been installed on your system, click on ‘Continue Anyway’
3. Click ‘Yes’ to all subsequent questions
4. Allow the update to fully run to the end
5. When update is complete, disconnect the USB from the computer and phone
6. Remove and reinsert the phone battery
7. Power on your Sony Ericsson P1i phone
8. Congratulation!!!

NB: since the phone is not powering on, you may not be able to know whether the battery is fully charged. Hence, you will need to use a Sony Ericsson Deskstand. Connect the Battery Charger to its slot on the Deskstand and the USB cable to its slot simultaneously. This enables the battery to charge while the update is also running.