User Form Image1

I'm using Excel 97. I have a userform with a picture (image) attached. When the userform runs the picture appears as it should on my PC I actually have an auto_open macro which has the code userform1.show. I've emailed the workbook to various people all using Excel 97. Some open the workbook and the form appears with the picture others get an 481 invalid picture error. Is there any settings not set on the failed PC. I've checked addins and references in the VBA all are the same as mine. And is there anyway to check to see if the picture is attached to the emailed file apart from running the macro.