PDF Form values are randomly incremented by 1 at client! Bug?

Hello,

I have a ColdFusion web application that, by client request, creates a copy of a PDF (which has about 100 empty form fields), then fills the fields with data via FDF like so:

<cfpdfform action="populate" ...>

     <cfpdfformparam ...>

     <cfpdfformparam ...>

     ...

</cfpdfform>

This PDF then sits on the server and is offered as an HTTP download to the requesting client.

I had a client tell me that she downloaded a PDF created this way, and some of the fields had a their ASCII values incremented by 1. For example, what should have been "599465-GU" in one field was displayed as "6::576.HV". According to her it was a sporatic problem that appeared throughout some of the PDF's form fields. I have never heard of this problem before from clients.

I looked on the server at the PDF that was sent to her (that was created by the server, sent to her as an HTTP download, and still sat on the server) and it appeared normal to me!

What I want to know is: Where's the problem likely coming from? Is the problem from her Adobe Reader software (corrupt install), or is the problem from the PDFs that she's receiving?

I don't know which version of Adobe Reader she has, but it's either 9 or 10. ColdFusion 10 on the server.

Any insight would be most helpful. My suspicions are that the problem is entirely client-side, but I want a second, third, fourth opinion.

Thank you!