I've had this problem for some time and I believe it is an Outlook issue.

In my other MS apps, Word, Excel, IE6, when I have an open document or web
page I used to select File | Send To (in Word and Excel) Send in IE6 and when
Outlook is open a new email was created with the document as attachment. Now
I get a dialog box saying only "Operation has failed". How can I fix this?
I've done Outlook Help | Check and Repair several times.

Thanks,
philr