Summary Link Webpart issue in MOSS 2007

On my MOSS 2007 intranet site, a particular user is getting an error when he creates a new link or modifies an existing link in the Summary Link Web Part. This is the error that pops up:

Object reference not set to an instance of an object. at
Microsoft.Sharepoint.Publishing.Internal.WebControls.ToolbarViewSelectionDropdown.CreateChildControls()
at System.Web.UI.Control.EnsureChildControls()
at Microsoft.Sharepoint.Publishing.Internal.WebControls.ToolbarDropdown.OnLoad(EventArgs e)
at Microsoft.Sharepoint.Publishing.Internal.WebControls.ToolbarViewSelectionDropdown.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.AddedControl(Control control, Int32 index)
at System.Web.UI.ControlCollection.Add(Control child)
at Microsoft.Sharepoint.Publishing.Internal.WebControls.Toolbar.Add(ToolbarObject objItem)
at Microsoft.Sharepoint.Publishing.Internal.States.AssetPickerDetailState.initToolbar(Toolbartoolbar)
at Microsoft.Sharepoint.Publishing.Internal.States.AssetPickerDetailState.Configure(SMObjectList objectlist)
at Microsoft.Sharepoint.Publishing.Internal.WebControls.SMObjectlist.Handle_LoadCompleteEvent(Object sender, EventArgs e)
at System.EventHandler.Invoke(Object sender, EventArgs e)
at System.Web.UI.Page.OnLoadComplete(EventArgs e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

This happens everytime this particular user(only) is in the Summary Link Web Part, New Item or Editing an Existing, and clicks Browse next to Link URL. However, he does not get this error when he clicks Browse next to Image URL.

 The appropriate permissions are in place but what is weird is that I tried adding and modifying links and it worked for another user that is in the same security group. The problem seems to be isolated to his account for some reason (fyi - We are using Windows Authentication).

I do know that he was previously exporting and importing web parts to keep the same formatting, which could be a possible cause. Additionally, he was in Sharepoint Designer and swears he didn't modify anything. Can anyone help shed some insight?

P.S. I have tried the following with no luck:
Please try to use stsadm command to export then import the current site which contains the problematic  summary link web part:
stsadm -o export -url <URL name> -filename <export file name>  -includeusersecurity -versions 4
stsadm -o import -url <URL name> -filename <export file name>