This is common after downgrading from Outlook 2007.
See http://www.msoutlook.info/question/137

--
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more

http://www.msoutlook.info/
Real World Questions, Real World Answers

-----

"Lori" wrote in message
...
I uninstalled the trial of office 2007. I then tried to reinstalled
outlook
2003 (Teachers Edition) and outlook 2003 still doesn't come on b/c of the
message below.

Should I just buy outlook 2007?

"Diane Poremsky [MVP]" wrote:

No, its not windows mail that is causing problems. Do you have a trial of
office 2007 installed?

--
Diane Poremsky [MVP - Outlook]
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"Lori" wrote in message
...
I recently got a new computer with Vista Ultimate.
I then installed Office (Teacher and Student Edition - 2003). All the
programs (Word, Excel, PP and Outlook) installed.

When trying to run Outlook, the following message is received:
"Cannot start Microsoft Outlook. Caused by installing other messaging
software".

If this because you cannot run windows mail (comes with Vista) and
outlook
2003 at the same time? If so, can you give a recommendation as to how
to
get
outlook - would you need to get an upgrade to outlook 2007.

But using outlook 2007, would this run simultaneously with windows
mail.