I was having the same problem after migrating my perl application to a new machine and found the following discussion of a similar problem:

http://forums.whirlpool.net.au/forum-replies-archive.cfm/843943.html

The recommended solution was to force a re-install of Scalar::Util and that did the trick for me.

In reply to Re^4: Open page error for PDF::API2 by rkocherl
in thread Open page error for PDF::API2 by ikkon

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