[CentOS] Help with thread Centos 6.4 won't reboot on install

>       Have inconsistency in getting it to let me login. Yesterday no
> luck. At '$ runlevel'  got  5    3 so it must have been at runlevel 3.
> startx no help, back to blue screen. Today, just started it first time
> and it booted right to GUI login screen. All is OK that has been set up
> like email, FF, printer etc. Checked Pref/System/Network Connection and
> the box is greyed out. Pref/SysytemNetwork Proxy only 'Direct Internet
> connection' is ticked. Everything else is greyed out. Ran updates also.
> This happened a few days back and was fine as long as I stay logged in.
> Re-boot or shutdown was not good. Couldn't log in again. Then
> surprisingly today it is back.  WTF ? Other HDs are OK and work reliably.
>
> Bob

Just a random thought that may trigger something in the wider brain trust:

At various times you have mentioned that you had "shutdown".  How did you 
do a "shutdown" both from Gnome and from the terminal?

The reason I ask is that Linux supports more than one kind of "shutdown", 
but they are not all equal.

The safest one is labeled something like "Turn Off Computer" (on KDE, not 
sure what wording Gnome uses) or you type "halt" at the command line, and 
it takes a good part of a minute to shut down.  On many computers you can 
achieve the same effect by pressing the power button for LESS than half a 
second (quick poke).

For some laptop users, just shutting the lid on the laptop is how they do a 
"shutdown".  This does NOT shut down the computer, but just puts into 
"suspended animation".  When you wake it up, it tries to resume where it 
was before you shut down.  This is also sometimes labeled "hibernate" on 
GUI screens (I have not idea how to do it from the command line).

Hibernation works well on some laptops, but is very problematic on other 
laptops.  Basically Linux tries to make a complete record of how everything 
was set when it is commanded to hibernate, then write its entire memory 
contents onto disk, then take a nap.  When you wake it back up it tries to 
restore its memory from hard disk, and put all the hardware back the way it 
was before.  Laptops are notorious for having special hardware, specific to 
a particular model, that has some secret setting that has to be restored. 
Until the kernel maintainers find out about and accommodate each of those 
secret settings, the laptop may get out of bed on the wrong side, and be 
very contrary.  For this reason, whenever you are having any kind of 
problems, one of the first things to do is to NEVER do anything except turn 
it off all the way with a full, long shutdown.

Another (problematic) way to "shutdown" is to hold down the power button 
for about 5 seconds.  This is equivalent to wanting someone to go to bed, 
but they don't want to, so you hold your hand over their mouth until they 
pass out, lay them in a bed, and say they "went to sleep".  Yes, the 
computer is "shutdown", but it didn't have time to do it in an orderly 
manner, and so there may be a mess to clean up when you power it back up.

This may be entirely irrelevant, but if not, it may be helpful, especially 
when you sometimes seem to be describing a situation where you only can get 
into gnome if the last time you shut down you were using the command line. 
  Also, the one time you described the computer starting up very 
quickly--this is the (desirable) characteristic of hibernation.  If your 
"shutdown" is different from the command line than it is from the GUI, then 
you may be facing a hibernation (or similar) problem.

Ted Miller