Vostro 1400, many problems and issues

I have a Vostro 1400 that I got in Dec. 2007.  It was fine and I loved it for the first year of it's life.  Then in late Dec. 2008 the video card died and nothing would display.  Dell replaced the entire motherboard and my disc drive which was rattling.  Things were fine after that until the other day.  Many issues have just came up and I just cannot figure out.

1. The Vostro does not sleep or hibernate at all.  I have my power settings set to go to sleep when I close the lid  (under all conditions) and hibernate while on battery power after 15 minutes of not being used.  When I close the lid nothing happens in any case on a/c or battery power.  It just sits there with the lights on and everything, fans blowing, HDD making sounds.  I lift the lid and it's still on.  If I try to manually put it to sleep through the start menu, nothing happens; it just sits there.  It also will not hibernate under any conditon.  All I can do is restart and shut down, this is very annoying. 

2. During start up while the screen is black it just looks terrible.  There is back light bleeding all over, the screen doesn't even look black.  When Windows boots it looks OK then after about 5 seconds the entire thing dims.  Colors are totally washed out and the whole screen has a grey look and is just dim.  The brightness is all the way up.  If I hook it up to an external moniter that also goes dim, and I know there is nothing wrong with my external moniter.  I can mess with the external moniter's settings to make it look a little better but I shouldn't have too. 

So is the video card dying yet again?  Why won't it go to sleep?  I have considered reinstalling Vista with my discs but with the screen problem it makes me thing something else is wrong.  Should I just call Dell and ask for the entire thing to be replaced this time?