PC Won't boot after windows screen

[rotteneggz]

Hi,
My PC just reboot out of no where and now it won't get past the windows loading screen, it just reboots again. Now i did a little research and came up with it being a RAM or a Hard drive problem. I really think it is a hard drive problem because one the first loading screen where it searched for master and slave devices, it detects my hard drive and says it is BAD and needs to be replaced. Before i go out and buy a new hard drive, i was wondering why i am able to log into safe mode?
If i am able to get into safe mode, doesn't that mean there is nothing wrong with the hard drive?

Thanks

 

[Lord Nassirbannipal]

When you get into safe mode, back up your data (if you haven't already) and run a hard drive diagnostic utility.

Try hitting F8 when before booting and select "Last Known Good Configuration" and see if you can boot into Windows that way.

 

[Jorona]

If your Hard Drive is reporting a smart failure, stop trying to get into windows and back that thing up before it completely quits on you.

 

[Old Hippie]

Have you bothered reading the Basic TSing Guide?