WSS error when trying to check out PDF files

I have a strange issue in WSS 3.0. It uses forms-based authentication and is under ISA. I can check out any file except PDF files. When I check out a PDF I get "Value does not fall within the expected range." I suspect this has something to do with ISA and where SSL is terminated. I have had problems before where links that should be https were showing up as http in the site.

For the present issue I have tried various AAM settings and nothing seems to make any difference a开发者_如何学Pythont all in the operation of the site.

I saw the "value does not fall within the expected range" the other day in a forms service form that had an upload field. The fix for me was to add the enctype= multipart/formdata to the application.master form tag. Probably unrelated but it's worth looking into.

We have had this error when trying to save a file to a location that does not exist.

Check that it is PDF files that are failing, not that it is files from list x, where all PDF files are only in list x.