Some machines will do exactly what you wrote if the HDD is bad in some odd way.
Removing the hard drive and trying again may show it to behave a little better. Also, if that doesn't help, remove both sticks of RAM and put the original back in.
Windows vista home premium
2gb of Ram (updated in september from 1)
everything else is stock
I have a problem where my laptop will not boot or show anything on the screen. what will happen is that when i press the power button, everything will light up like normally then it will shut off and cycle like this every 10-20 seconds. I have tried to do a hard reset, as well as trying to boot into bios, nothing works. Pressing f10 does get it to stay on but the hard drive light does not stay illuminated telling me that it is not being able to read the hard drive, so i tried to re-seat the drive but to no avail. also i tried hooking an external display and still no picture. I know i have a virus because i was trying a youtube to mp3 converter that even though it would uninstall, the icon would be glued to the desktop saying that i need special permission to delete it. then out of no where it disappeared. so i shut down like normal, then when i went to restart, it started normally, but there was no response from either my track pad or my keyboard (external ones did however work). but know i cant even boot to remove the virus. any help would be greatly appreciated