Random problem printing PDF files generated on iSeries

I have only seen this a couple of times, but I have seen it
myself so I know it is happening.

A user opens a PDF file generated from the iSeries and
located in the IFS

 

Adobe opens it fine and it displays fine and 99.9% of the
time it prints fine. 

On a rare occasion when the user prints (from adobe acrobat
reader) all the characters on the page are garbled up.

The correct number of characters are printed and they print
in the correct location but it is totally unreadable because
the characters are 

Randomly transposed.

And this happens rarely and it's not specific to one PDF
file

 

The user can select to print again (still has file open in
Acrobat Reader) and it may print garbled again or it may
print fine.

The users know if the page is garbled to just print again
until it prints fine (usually takes 3-4 prints).

Then everything is fine for weeks.

 

All of this without closing Acrobat Reader.

It happens on different printers (not strictly occurring on
a specific printer)

 

Anybody ever seen anything like this?

 

Allen