How much RAM are you operating? What OS version? Have you trashed preferences? Have you investigated for any odd, old, or corrupt fonts?
You mention < and / in the fields...those are not used in the column headers, are they?
I would recommend not using Preview. Often enough, it will corrupt the merge document and about the only recourse is to copy the elements into a new file and resisting using Preview.
Win7 SP1, 12GBRAM...
I tried clearing the preferences, but I don't have admin rights on my PC and the task needed them. I did delete the "InDesign Defaults" file from the c:\Users\<username>\AppData\Roaming\Adobe\InDesign\Version 7.0\EN_US\ folder.
I copied the elements to a new document, linked the CSV and saved it. Same error.
The < and / are not in the column headers.
The only font is Arial.
Does it work to merge to a new document versus to pdf?
Merging to a new document takes a significant amount of time, but it does work. However, when I try to export to PDF, the program locks up. It creates the "holding" PDF file, but doesn't place any content in it.
Can you share the files? If so and you would like to keep them private, feel free to upload to dropbox.com or the like and send me a PM with the download link. I would be able to take a look over the next day or two after receiving the ZIP.
Oh. You also mentioned CS5 in the opening post. Lowest version I have is 5.5 and so that may skew the results.