it looks like the error is produced by the line 739 of fckimagegallery.aspx (abbriviated):

Dim intSize As Integer = txtfile.ContentLength
if portalDB.GetPortalSpaceUsed(Me.PortalSettings.PortalId) + intSize) / 1000000) 

if the space used (in Bytes) exceeds maxint, the error occured. I will log this into Gemini.

Nina: it is definately another error than in the other thread, and not an issue of FCKeditor, but of the DNN provider (and I expect it will be fixed in next version).

Thanks for logging the defect.  It's a show stopper for us.  I (well, my users in particular) really appreciate the quick response.  Thank you.  :-)

Craig