Database screwed up by Conversion Util?

Hi

I have just upgraded fra V6.34 to V7.01. Everything seemed to work so I used the conversion tool to convert the database. After doing to according to the documentation, I uploaded and logged into the new forum. Everything seems to work and looks great. I have even upgraded the language files and buttons to danish.
BUT, when I create a new post in the forum I get either of the followin messages:

Microsoft JET Database Engine error '80040e21'

The changes you requested to the table were not successful because they would create duplicate values in the index, primary key, or relationship. Change the data in the field or fields that contain duplicate data, remove the index, or redefine the index to permit duplicate entries and try again.

/temp/forum/post_message.asp, line 609

or

Microsoft JET Database Engine error '80040e21'

The changes you requested to the table were not successful because they would create duplicate values in the index, primary key, or relationship. Change the data in the field or fields that contain duplicate data, remove the index, or redefine the index to permit duplicate entries and try again.

/forum/post_message.asp, line 749

And then if I log back in, the post is created, but only with the subject. There is no message body. The forum tells me that there is no info on this post in the database.

PLEASE HELP!!

PS. If I leave the database unchanged, everything works perfectly. So the problem happens during the conversion of my V 6.34 database to the V7.