Inspiron 6400/e1505 locks up, won't start, ideas on, HELP!

Laptop, Inspiron 6400, purchased Sept/06, Core2Duo T5600 BIOS - Phoenix (4/02/07) ATI X1400 2048MB memory (bought 2 sticks of RAM, not hte cause of problem, worked fine for 2 months before)

August of 2007 I spilled coffee on my desk, it seeped underneath my comp, had complete care, sent it back in. On the order sheet they said they replaced pretty much everything but the chassis (H/D, mobo, CPU, RAM, etc.) Now, my warranty expired October. When I got it back early Sept, for some reason, it would lock-up after usage most of the time. This problem was solved by using fan control software, I thought the problem was heat and lo and behold it was. Suggested that heatsinks or something wasn't installed properly, but I coudln't afford to send my laptop in again, as it was working fine after I started using I8kfanGUI.

Now, fast forward to November. Every so freaking often, my comp will just LOCK UP. just freeze. This happens mainly if i lift my computer or move it when its plugged in and on - but still happens when on battery or just left running. Temperatures are around the 40-55 degrees celsius range for any of the lockups. Here's the weird part - when I try turning hte comp back on, the power light comes on, then goes off. OR, it comes on, but nothing boots up, just a black screen, and then turns off. Don't know why exactly, but after a couple of attempts or leaving hte comp alone for minutes, hours, days, it will boot up again. HOWEVER, sometimes it boots up again right away so i'm very confused as to the cause. I'm suspecting a faulty mobo. Does anyone know what the problem is wiht my comp?

The one thing I notice is that it locks up alot more frequently when it's plugged in, I think it's only locked once on me when not plugged in (but won't boot up regardless if its plugged in or not). any help is appreciated. No warranty = frustration. Should have sent it back when I realized there were probably faulty repairs.

As of a few weeks now, I don't take my laptop anywhere, I just have it sitting home plugged in, with a targus coolpad thing. I haven't had any lockups or freezing or non-booting for a few weeks now.

 

bumppppppp

 

up, please help!