Invalid character in a Base-64 string.

Hi ,

In my process i am using 'SharePoint 2003 Multiple Document Upload' event to upload a file from InfoPath form into SharePoint document library.

This works perfectly fine for doc,pdf,xls .... but fails for JPEG,GIF.
If i upload any JPEG,GIF images in InfoPath and submit the form, under error profile in k2 service manager, an error is shown "Invalid character in a Base-64 string".

Pls advice.

Siva