I use an iphone 3g and in the past week have had to restore 5 times.
Jailbroke with the pwage tool. the phone is restored succsesfully however, after installing a few packages with cydia, the phone will freeze or shut down automatically. Either remains froze until i power it off or after shutting down by itself it will freeze and remain stuck at the logo screen during power up????
any suggestions as to what I may be doing wrong?

It looks like the jailbreak process worked flawless. Your problem is Cydia, I think

When you jailbrake your iPhone did you choose to install Cydia and Icy or just Cydia?