Tru64 5.1B patch kit 5 installation problem

I'm trying to upgrade Tru64 5.1B from patch kit 4 to patch kit 5.
There's an error which I haven't been able to solve (see below).
The file /etc/pmgrd_iorate.config was modified by me for disk
monitoring, so I've renamed this file prior to installing the patch kit.
I've also done a dupatch baseline operation, but this didn't
solve the problem with /etc/pmgrd_iorate.config.

Any suggestions for a resolution ?  At the moment that patch
kit installation refuses to proceed because of this problem :-(

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Problem installing:

  - Tru64_UNIX_V5.1B / Network Patches:
         Patch 26020.00 - SP05 OSFCLINET540 (SSRT3653 SSRT2384 SSRT2275 ...)
         ./etc/pmgrd_iorate.config:
                 does not exist on your system,
                 however, it is in the inventory of installed subsets.

This patch will not be installed.

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Thanks a lot,
Ole H. Nielsen
Technical University of Denmark