Outlook 98 - Cannot make a new task

[Fern]

I need some help.
In Outlook 98, running on Windows XP SP1 I cannot make a
new task. I get an error message."Could not complete the
task. one or more parameters are invalid".

All parameters are filled out.
I have Office 97 and Outlook 98. I uninstalled and
reinstalled Outlook.

thank you...
Fern