It seems you have downloaded the package for
Mandriva-2011 ... Why you expect it will work on PCLinuxOS ?
Install the available packages from PCLinuxOS repo:
ptyhon-2.6libstdc++6and then rerun getvirtualbox script.

AS
He only did that after the get-virtualbox script failed. And, in Hawk's defense, many PCLOS packages do work on Mandriva.
Looking at the reported failure:
If I open a cli and run the getvirtualbox script I get ...
./VirtualBox-4.1.8-75467-Linux_x86.run: line 1: syntax error near unexpected token `<'
./VirtualBox-4.1.8-75467-Linux_x86.run: line 1: `<HTML></HTML>'
it appears this is not the correct
VirtualBox-4.1.8-75467-Linux_x86.run, because that file start with the follwing lines ...
#!/bin/sh
# This script was generated using Makeself 2.1.5
CRCsum="1781401554"
MD5="bb81460d86d104509fb3add401c6d3b0"
TMPROOT=${TMPDIR:=/tmp}
label="VirtualBox for Linux installation"
....
Based on the error I guess the getvirtualbox script downloaded an HTML page ...

This could be related to some recent changes on VirtualBox website, see news 20 Jan 2012:
https://www.virtualbox.org/Whenever getvirtualbox is the cause of the error, the right version to manually download is the "
All Distribution".
https://www.virtualbox.org/wiki/Linux_Downloadshttp://download.virtualbox.org/virtualbox/4.1.8/VirtualBox-4.1.8-75467-Linux_x86.runI see no point in searching trouble by using other's distro versions.
AS