MacBook Sleeps but doesnt wake up.

The only thing i did to the macbook is install a new hard drive (seagate 160g sata 7200rpm) and ram 2g. Anyways i leave my macbook running for a long time, like over night or while im at work, and when i come home the white light is on steady and screen is off, nothing i do will wake this thing up! i have to reboot everytime. the power save setting are screen saver at 7 min screen off at 20 min and computer to sleep in 1 hour. but i have at lease 3 programs running when i leave. I have toast making a dvd (it never finishes before the computer sleeps, as a result i have many coasters) and i have a torrent program running as well. anyway, if any of you are experiencing the same kind of problems or have a solution please let me know. thanks.

Oh this happens even if the battery is out.

This happens to me every now and then, but not as often as you mentioned. I talked to a guy at apple and he said that i should bring it in.. but i already know they're not gonna be able to reproduce the problem and just have me reinstall OSX...

side note; if you leave it on all the time and its at home while your gone, why not adjust your power settings so it never sleeps and keep it plugged in with the battery out.. you'll be able to burn your cd's when your gone, then when you wanna move it around, plug the battery in, and change the power settings to whatever suits you.

also this may help, go to disk utility and select your HDD, then click on repair disk permissions, i do this every month or so and it always finds and corrects improper permissions (don't know if it helps much but its better putting them the way mac osx wants them..)

looks like it was bad ram and the kernal keeps crashing the computer so it never wakes up.

This happened to me the other day, but it was the first time since I first got my Macbook a few months ago. Hopefully it won't happen again.

Still happening!