PST file in Outlook 2007 over 3gigs

Greetings experts!

I recently upgraded a user from Office 2003 to 2007. He's our development director and has an enormous amount of archived data, which he claims he needs to have access to regularly. When I made the change, I uninstalled 2003 and installed 2007.

I browsed to his pst file (on his local machine) and set it as the autoarchive file, and then went to run the import personal folder tool, but it took a very long time and eventually crashed his machine, so I had to abort it part way through.

I'm currently trying to get it started so it can take its own sweet time this weekend, but now I'm getting an error that "This Personal Folders file (.pst) is already in use in the current profile.", which is partially true of course, but it never finished importing the data, so there's only a fraction of the message history showing up in Outlook.

Is there a way I can remove this from the profile and start the import process again other than doing another install of Office?