Outlook 2003 - extend.dat error

Hi. Just got my new XPS 410 and Outlook was pre-installed. I am running Windows Vista premium home edition and needless to say, I can't find anything and lots of programs are incompatible.  MS Outlook was working fine, until I imported my email messages then I get this error:

 

"An extension failed to initialize.  Can't open file: extend.dat.  The file may not eexist, you may not have permission to open it, or it may be open in another program.  Right click the folder that contains the file, and then click properties to check your permissions for the folder.  You don't have appropriate permission to perform this operation."

 

And the other thing is that I keep getting these annoying messages that keep prompting me to click yes to make changes because I am the administrator.  I called dell about this and they pointed me to knowledge base and the forums.  Help?