Could you also tell us exactly which version of McAfee you have installed? You post here in the
SecurityCenter 9.0 - 2009 forum, but this version is only available in some part(s) of the world.
If you have an icon near the PC clock like:
, then launch the Security Center:

Click on the "View Details" link and in the next window you see all the McAfee programs installed. Clicking on each of them will give you the exact version numbers. Include the version # of the VirusScan Scan Engine and DAT file.
Also, what version of Windows is installed?
- Windows XP: Go to Start > right click My Computer > click on Properties and on the General tab you'll find all the information, incl. any installed Service Packs.
- Windows Vista: Open Welcome Center by clicking the Start button , clicking Control Panel, clicking System and Maintenance, and then clicking Welcome Center.
- Check if your version of Windows is up-to-date at: Windows Update. Use the "Custom" button. This way you also get the "Optional" updates as well as the "Critical" updates/patches.
When you completely uinstall the McAfee software is the external hard drive accessable again? Before you installed McAfee software what antivirus/antispyware or security software did you have previously installed? What did you do with that? Uninstalled first?