[Gigi]

My guess is that the laptop is still fine and the problem probably lies with AC charger or the battery. To get rid of the screen flashes just change the brightness of the screen to the same level for both battery and AC.

Here are some ways to troubleshoot the problem:

1) Plug in AC and take out the battery. Does the computer start up fine? Does it stay on?

2) Only use the battery this time. Does the computer start up fine? Does it stay on till the battery warning comes on and the computer dies?

3) Using battery and AC, wake till the battery charges. When you take the battery out, at least on my dell, there is a button on the side that you can press and 5 LEDs light up to show the charge. If you hold the button the LEDs will indicate how "good" the battery still is. How many lights do you get when you hold the button? How many years have you been using that battery? Do you always keep it charged?

4) Use a friends AC charging cable, see if the problem still exists.

5) Use a friends battery, see if the problem still exists.

What are the intervals for the "switching"? Does it mostly use the AC power and then switches to battery for a little bit, or vice versa, or neither? How long does it stay in each mode before a switch?