I finally got a good download of the Velleman K4040 tube amp using an old version of Netscape as my web browser. Neither Safari or Explorere would handle it. Strange.
I went thru the manual quickly, gee 12 or more LEDs!! I don't think we will design along these lines. 
Frank
Safari on Mac OS X Tiger downloaded it fine first time. The pdf displays properly with Preview and Acrobat Reader. My Mac is an antique. It's a B&W G3 upgraded with a G4. So if it works for me... it should work fine for you.
Maybe you're just computer-challenged or something? It could be all those years working with HP UX. I hear it can cause problems with your mental health.

Maybe Steve Jobs hasn't blessed you properly? On the other hand, I've called him various rude names, so maybe you need to let loose with some expletives in Steve's general direction?

We've got an HP 9000 that's perfect in my opinion. It's sitting in the corner not even plugged in. (And it's a pretty healthy box, 4 CPUs and 16 GB of RAM...). hehe
I'm more of a Solaris guy myself, although Linux works really well. That HP UX and IBM's AIX are like another planet to me.
Oh, BTW, I almost never use IE on Mac OS X. In fact, I think I've only used it to verify problems you were having.
If you want an alternative to Safari, look at Firefox, Camino, or Omniweb. IE is evil. (And MS recently disowned it anyway.)