Inspiron 1545 completely freezing

I have a 1545 laptop and we let somebody borrow it for a couple weeks and I think she dropped it. any way, when I powered it on and it booted up, I could be using it and within the first 5 mins it would freeze. not like a sluggish system, but I would have to hold the power button to manually shut down. after a little tinkering I decided it was the hard drive bad ( a series of trials and errors led me to this decision) the system got to where I would barely load. Well during the trial and error, I found that while its running that ifs it is barely bumped ( such as sitting it down on the couch or counter, etc...) It would freeze completely again. Well I have replaced the hard drive and seemed fine until my wife let it sit for about 2 or 3 weeks in hibernate (its actually her laptop). I have checked the ram sticks to see if they are loose, but they seem nice and snug. I have tried tracing some of the wires and cannot seem to find any loose. Also, tonight, when I would have to reboot after holding the power button, the picture would not come up. I had tried shutting it off several times and restarting in a row, I closed the screen and opened it, and finally after about 6 or 7 restarts and shutting the lid 2 or 3 times, it finally started. after that happened I am now thinking the video card could be going bad...ANY IDEAS WOULD BE GREATLY APPRECIATED!:emotion-43: