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I am using Iphone 4, IOS 5.1.1., whenever I download any application from Cydia, my phone automactally start re-starting withing the gap of 5 to 7 seconds. Can anyone help me how should i rectify this........
Your phone is jailbroken, you can't get any help here. Check with the Cydia site.
Hacking your phone voided your warranty and right to support. Restore the phone in Recovery Mode: http://support.apple.com/kb/HT1808 so you will no longer be in violation of your license agreement and probably remove your problems.

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