BleepingComputer.com: Ie Problem...serious!

my internet explorer 7 keeps crashing on me,after about an hour or so of using my laptop,i hear a pinging noise wen i click on a link or web address,and it wont let me access it.
Not only that,but i cant get nothing to work at all wen this happens,control panel,,documents.........i even cant switch my lappy off via the switch off buttons in start,i have to manually press the power button,to switch off,this is proper doin ma nut in,and if anyone can help,id appreciate it very muchly!!!.
Also,my lappy works fine again,once ive rebooted!!??!?!? but only for another hour or so????

Well angie, let me ask you:

- Is the sound very high pitched?

- If so, does it come from your speakers or from within the laptop itself?

- Can you do ANYTHING else after the noise, besides click a link?

- Have you tried CTRL+ALT+DEL and pressing the red power button down right to turn it off there?


Thanks!