Hi Prabakar,

What I've found out is GetDesktopWindow() works a bit different in Vista: it does not accept the directory info in the third parameter. So you have to indicate the directory in the fifth parameter. Kind of an ugly solution, as I will have to place the PDF files in the same directory where the reader exe is. Not good, but this is the only solution I could find for the moment.
Thanks very much for your help!!

Same directory as the reader? Why not give the full address fo the file?

Like this,

Paths must never be hard coded. You must get them from Shell.

That's what I always do, but, it looked like the OP was not satisfied with it.

What if he can't move it from a particular folder? ( happens often when it is a shared computer)

Copying the pdf and pasting it on a specific directory just to make your program work is not a good option

And adding the program to that directory might be irritating. It will be annoying to see a document in my songs folder.

Sometimes we need to use full address, or at least to use environment variables.