I get the same error with SL-60-x86_64-2011-03-03-Everything-DVD1.
I verified the checksum, verified the DVD when I burned it, tested it dur
ing
the install - no errors.

"Error Installing Package: A fatal error occurred when
installing the dbus package.  This could indicate errors when reading the

installation media.  Installation cannot continue."

I read about the same problem with a Fedora installation, so I tried it
again without adding any repos, and less customization.

Then I got the same message with "dbus" replaced by "polkit-desktop-polic
y".

So I tried using an external DVD drive via USB - same problem.

So, I tried the install DVD SL-60-x86_64-2011-03-03-Install-DVD - I still

choke on "polkit-desktop-policy". By now I am doing just a "Desktop" inst
all
with virtually no customization.

So I tried it on a completely different system - same problem.

I may have the sequence a little mixed up, but at the end of a long Frida
y
night, I was getting the error on "polkit-desktop-policy" from Install-DV
D.
I get this in install.log :

Installing polkit-desktop-policy-0.96-2.el6.noarch
warning: polkit-desktop-policy-0.96-2.el6.noarch: Header V4 DSA/SHA1
Signature, key ID 192a7d7d: NOKEY
error: %pre(polkit-desktop-policy-0.96-2.el6.noarch) scriptlet failed, ex
it
status 127

Monday I tried the boot CD, SL-60-x86_64-2011-03-03-boot, and did a netwo
rk
install from ftp1.scientificlinux.org/linux/scientific/6.0/x86_64/os/ - i
t
finished within 2 hours without a problem. Maybe I will try the Live DVD
next time.

I have installed SL 5.x maybe dozens of time over the past few years and 
I
hope to install SL 6.x many more times - I love it for use in DVT of new
hardware. If there is any way I can make this easier, I would appreciate 
it
if I could learn how.

Thanks,
Harry

>> . fatal Error during installation of DBUS
>> . .iso was verified after download, burned on Windows 7 using native
>> Windows Disc Image Burner with verify disc after burning
>> . .iso was checked on target machine during installation
...
>
> Hi Larry,
> More information is needed about how you were installing.
> Particularly, did you select any extra repositories in the screen where
 you
> can?
> There is a known bug/feature that when doing an install from the Everyt
hing
> set of DVD's, you cannot select any extra repositories.  That is why th
ere
> is an Install DVD, which doesn't have this bug/feature.