I do wish you provide the screenshot of the error
instead. That way, I can see whole message of it.
Based on your description, it seems that you will needed to reinstall completely...
First, shut firewall and
anti-virus completely! (I know this is against the computer security practice, but... for odd reasons, freaking Norton/AVG/Mcafee block the Installer in their firewall and detect patches as Trojans...)
Then, try to follow the installing instructions here...
I do always wonder why they don't change/fix/update the installers yet... It's simply just so nuts to keep driving away players because of unable to install DWO... (Not to mention with increased amount of patches... players will also have to go through 15+ patches for another hour or two before actually able to play...)
Sincerely, Pan2011 ~ Pan2012 (April 9th, 2012)