Need some help

So.. i build a new system for my parents PC and im having some very interesting problems...

First off heres the system:
K8N Neo MSI board
Sempron 64 2800+ cpu
Rosewill 400watt psu
60gb Seagate HDD
512mb Corsair Value Ram
and i had a geforce 4 ti 4600 8x in it..

When i first powered up the system it booted fine.. but everything was pinkish. I was really confused.. checked the monitor cable.. and all was fine. Well, that wasnt a huge isue so i installed windows and set everything up. Well, when i turned it off later that night and came back the next morning.. and it powered on but wouldnt post. No matter what i did it wouldnt post. So i basically pulled everything out again, and put it back in and it still wouldnt post. So i pretty much unplugged and plugged in the the power cord and randomly messed with the power button and it started.. lol. So now i tried to figure out why this was happening, and i kinda thought it was the video card.. since it was all pink. So tonight i went and purchased a cheap geforce mx 4000 and installed that, and it wouldnt post right away. The weirdest thing was that the light on the cd drive was flashing. So i randomly turned it on and off and it started again. I wish to know why its still doing this. The new card did solve the pink screen problem, but when i turned it off about 10 minutes ago it didnt post again right away... So do you people think it could be the mobo or the cheap PSU? i really just want to get to the bottom of this. Thanks..

Due to the nature of what is happening I would have to say its the Power Supply...AND a cheap to test ...Rosewill is not known for Quality.Antec, Enermax are a couple of Excellent Quality manufactures.

So im pretty sure its the psu. I checked all the jumpers and they are correct. I have reseated both the vid and memory numerous times. I was messing with the tower, and i found that if i disconect the power cord for about 5 min and plug it back in, it posts. If i just turn it off and hit the power button, it wont post. So sounds like a psu? i'm going to go buy a new one and test my theory.

well.. its not the psu. I bought a antec 400 watt psu today from best buy, and it does the same stuff. So i'm assuming it's the board now becase memtest checked fine. So time to return the video card/psu and RMA the board.