Strange error updating boinc from 6.12.33 to 6.12.34

on 3 host of 6, as I have pressed Install I've got this:
1) Firefox, used for the dowload (6.0.2) shutdown immediately (all tabs and program)
2) nothing more from Boinc Install, window close, non final question to restart boinc
As I start manually Boing, I see that the release installed is 6.12.34
Everything is working fine.

Hosts are win-xp svp3.
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