Opening pdf files in SeaMonkey Mail

I am getting an error message when I try to open a pdf file I sent to someone else and myself, as a check. I have gone into preferences and chosen Adobe Reader 7 as the program to open the pdf but I still get the error message.
Here is the message:
"C/Documents~1/owner/local/temp/problem.pdf can not be opened because the associated helper application does not exist. Change the association in your preferences. "
I have both the Adobe Reader v.7 and the full Adobe Acrobat v.6 on my computer -- but prefer to use the Reader to open a pdf becuase Acrobat takes a long time to boot up.
Anyone have a suggestion how to fix this?
I also notice the download manager starts up when I try to open the pdf. I don't think that should happen, shoud it?

 

I think I may have fixed the problem by assigning the default SeaMonkey application for both the pdf and x-pdf files. It seems to work now, but I don't understand why it did not work when I specify the application and browse to its location.