If you are running the version of CF 9 that you have mentioned in your post previous (9.0.0.251028) then you are going to need to patch your server!
The issue you are having was a bug (Described not so well here - Bug#3040314 - Bug 80390:I have some corrupt PDFs ). It was fixed in build 9.0.0.263374.
Unless you really cant, I would recommend updating you CF9 instance to at least 9.0.2 anyway.