Apple rose $2.33 on Friday trading to $142.33 after brokers Piper Jaffray raised its price estimate for shares of the maker of the iPhone and the iPod music player 28% to $205.

"A tidal wave is coming in 2009, " said analysts Gene Munster and Michael Olson in a report published Friday.

"One thing we learned with the iPod is that when a device is game-changing, the demand will come."

Duke University, however, confirmed the worst fears from technology research firms that the iPhone may pose a security risk to enterprise networks.

Just 150 of the iPhones on the Duke campus in North Carolina have managed to wreak havoc with the school's WiFi network. One of the big selling points of the iPhone is its ability to connect easily to the internet using WiFi. But iPhones at Duke are trying to reach a router address that isn't there. When they are unable to connect, the iPhones flood the network with up to 18,000 access requests per second. The result has been the temporary knockout of part of the campus network for 15 minutes at a time.

It amounted to a socalled "distributed denialof-service attack", Duke's IT professionals told website CIO Today.

This is happening at a time when the university is on a summer schedule with just a fraction of the amount of students and faculty who will be returning in a few weeks.

When classes resume in August "this would be devastating", Kevin Miller, the school's assistannt director of communications infrastructure, told the website.

Other security experts said that the problem could be down to factors other than the iPhone, possibly to do with the Cisco wireless network being used by the university.

Ironically, Cisco had threatened to sue Apple over the use of the term iPhone, as it said it had developed a product with that name years before.