Can the old PDF's still be opened in Acrobat 5? Do you get the error just in Acrobat Reader 5, or in full Acrobat 5 too? Or does Acrobat 9 not want to open the old files?
One other thought - file size, and location. Are the files large, and on a network drive? See if they will open on the problem machines if they are copied to a local drive. And if they're really large, is there enough free disk space on the machines where they won't open?
File sizes   10's of MB, 100's of MB, or GB ??

Fred Wagner

  

Fred as far as I know there isn't a computer one that has Acrobat 5 installed on it any more.  

All our machines have 9.

All our files are on a network drive.  

We are currently going thru our old paper files and verifying that the electronic versions are correct.  Then we are tossing the paper.  

When we find a missing page or a bad image we rescan the paper - this is where we are coming into issues.  Adobe will crash before we can get the new image into position or sometimes we have even had documents when saved go from 7200 kb to over 4,000 mb and some just won't do anything.

Like I said one side says it is the wide variety of how the documents were originally scanned or being read and the other side just says it is corrupt.

If we don't know how these documents are getting corrupted and which side is correct - we could very well lose a file with no backup to restore since the paper version is gone and who knows when the document actually got corrupted to try to restore from a network backup if that tape/disc still exists.

Monster PDF's over several hundred MB cause huge problems over a 100M/B network. You'll find that the PC swap files are usually not big enough to handle them.
A way to reduce file size, besides dividing them in two, is to copy the file to a folder on a local drive, then open it in Acrobat, and Save As to a JPEG2000 (.JPF) file. Once that's done, close the original file, and Create a new PDF from the collection of JPF's that were created. There will be a JPF for each page of the original. Then save the new PDF. It will be 4 to 12 time smaller than the original. if the file included OCR-able text, run the OCR Text capture and save another 10% on file size when you save it.
If the problem involve large engineering drawings, you may need to change the orientation so they're very tall rather than very wide before you can do the JPF feature.
Another reason to compress the PDF's for network storage is that when a user tries to open a monster file, it clogs the network for everyone else.
Another solution you might want to consider is a Document Management system. Laserfiche stores image files as multi-page TIFF's rather than PDF's, and serves the pages across the network individually, rather than forcing the workstation to open an entire file. The indexing for the document is kept in a master database, so you can still search for a word, and be fed the pages where it occurs from the list of hits.
As you can tell, we've had lots of experience with this issue, and with solutions to it!

Fred Wagner

  

Thanks Fred I will pass the information along. Personally, I like the document managment system idea.