Laptop crash at random intervals. Power Problem.

Hi, I just wondered if anyone could help me.

I brought a HP Pavilion laptop from ebay quite a while ago now, the only problem listed was that the battery didn't work. The laptop worked fine for months and then it started to crash, when it crashed I couldn't do anything, the mouse wouldn't move and none of the keys would work either so all I could do was hold the power button in to shut it down. The charge light seems to flash just before the laptop crashes. I thought the problem might of been with the battery so I brought a new battery for the laptop. It still wouldn't recognise there was a battery plugged in, sometimes it won't have a red cross on the battery but will say "plugged in but not charging". I have noticed now that when the laptop does crash if I unplug the charger for a second and plug it back in (as the charge doesn't hold on the battery) the laptop will start working again. I was thinking the problem may lie with the charger or the bit inside the laptop the charger plugs into. If someone could help me I would be very grateful.

Thank you, Andy.

I brought a HP Pavilion laptop (FIRST MISTAKE...)
from ebay quite a while ago now, the only problem listed was that the battery didn't work. (NO COMEBACK ON EBAY... 'BATTERY DOESN'T WORK' IS A COVER-ALL FOR A NUMBER OF ISSUES)
The laptop worked fine for months and then it started to crash, when it crashed I couldn't do anything, the mouse wouldn't move and none of the keys would work either so all I could do was hold the power button in to shut it down. The charge light seems to flash just before the laptop crashes. I thought the problem might of been with the battery so I brought a new battery for the laptop (NEW, HP ORIGINAL OR THIRD PARTY BATTERY?)
It still wouldn't recognise there was a battery plugged in, sometimes it won't have a red cross on the battery but will say "plugged in but not charging". I have noticed now that when the laptop does crash if I unplug the charger for a second and plug it back in (as the charge doesn't hold on the battery) the laptop will start working again. I was thinking the problem may lie with the charger or the bit inside the laptop the charger plugs into. If someone could help me I would be very grateful.(WHAT HAPPENS IF YOU RUN THE LAPTOP ON MAINS, WITH BATTERY REMOVED?)
IF YOUR REPLACEMENT BATTERY IS NON-HP THEN YOU NEED TO GET AN ORIGINAL HP
IF IT'S AN HP, THEN (IF IT'S NEW) YOU PROBABLY HAVE A MORE SERIOUS PROBLEM AND SHOULD THINK ABOUT SELLING IT ON (WITH "BATTERY MIGHT NOT WORK" WARNING!)

ye its a third party battery, i couldn't find anywhere to buy a hp battery, could you recommend anywhere please? just don't understand how it worked with a non-working battery before then started crashing. It does crash with no battery inserted as well (just on the ac) which is why i thought it must something to do with the mains. thank you for your help by the way i really appreciate it.

It might be helpful to supply some more info:

1. System model / specification / OS version
2. Exact description of what happens when it "crashes". Any errors? Does the screen go blank? Any other indicators - HDD LED flashing excessively eg...
3. What changes were made around the time your laptop started to "crash" - any SW installed? Any HW added / upgraded?
4. If you force it to power down, does it reboot successfully right away?
5. Any other symptoms? (slowing down? excessive fan noise etc)

I am thinking that the battery is a red herring and the problem lies elsewhere, hence the need for more info...