Then I find that Paintbrush will not open it in any format. Any computer we try it on does exactly the same thing. How the hell did that change formats while being sent?
They came as logo.jpg, font.jpg, and wildcard.jpg. When the zip file was opened, clicking on anyone of those pictures resulted in "cannot open bla bla bla" error. If the files were extracted and placed in a folder, the only thing that will display the picture is Microsoft's "Image Viewer" program, providing I rename the file extension to BMP. When I do that, the thumbnail picture will come up. Figuring I had the problem solved, I sent the picture back to the owner in a BMP format, and it came as a JPG attachment through his ISP. The pictures will not open on his computer.
Then I find that Paintbrush will not open it in any format. Any computer we try it on does exactly the same thing. How the hell did that change formats while being sent?
Incidently, this zip file and its contents were scanned for viruses, and it was clean. I have Windows ME on my machine, he has Windows 98 on his. The other computers we tried it on had Windows 2000 Professional, and another had Windows 95. They all did the same thing. Basically, nothing! Just for the heck of it, I tried the *.pub, and the *.pdf. No progress made.
Is there a oddball picture format that I don't know about? Could it have been a Mac format of some sort? I never had this one happen before....
Thanks - Paul
What I don't understand is how the filename could be changed while it is INSIDE of a ZIP file! Maybe the sender just doesn't know exactly what he is doing? No matter what, I sense that something very evil and deadly is going on! 
Paul
Normally, a credible graphics program will sniff out the correct format of a file if it doesn't even have an extension. I've had Mac users send me Macromedia Freehand files that have come in with no "dot-three" DOS style extension. I drag the file into Freehand's open window and the file opens up fine (provided they used the Mac-equivalent in terms of fonts I have on my PC, or converted them to outlines).
I agree it really sucks when an ISP or some other piece of software changes your file suffix or the file(s) itself into some other kind of format. Any ISP worth a damn should allow multiple attachments without converting it into MIME format. They should basically let you send exactly what you want to send provided it doesn't go past their bandwidth limits or include any malicious code like viruses.
I really have to say I've seen some funny things users do at times. Some people out there think if they simply rename a file suffix to something else the computer will automatically convert the image to that format. I'm not kidding. I've had people send me JPEG images with the suffix renamed to "CDR", "EPS" or "AI" thinking that alone would turn their bitmap image into a vector object. It is almost as funny for someone to simply embed a JPEG into a Freehand, Illustrator or CorelDRAW document thinking the same magical conversion will happen. "But it is a CorelDRAW file," they whine. And I say, "it still isn't vector and the vector digitizing fee will still cost you $50 per hour."