FireBird - wrong page type

  boa noite,
estou com um problema parecido com o deste post
http://forum.devmedia.com.br/viewtopic.php?t=6933&sid=0ee5cb83b588f7dd01d92c2626d76d02

segue os procedimentos tomados:
C:\Arquivos de Programas\firebird\Firebird_2_5\bin>set isc_user=sysdba

C:\Arquivos de Programas\firebird\Firebird_2_5\bin>set isc_password=masterkey

C:\Arquivos de Programas\firebird\Firebird_2_5\bin>gfix -m -i c:\felipe\bf.fdb
database file appears corrupt (C:\FELIPE\BF.FDB)
-wrong page type
-page 4790 is of wrong type (expected 3, found 0)

C:\Arquivos de Programas\firebird\Firebird_2_5\bin>gfix -v -f c:\felipe\bf.fdb
database file appears corrupt ()
-bad checksum
-checksum error on database page 4790

C:\Arquivos de Programas\firebird\Firebird_2_5\bin>gbak -backup -v -ignore c:\fe
lipe\bf.fdb c:\felipe\bf.fdk
gbak: ERROR:database file appears corrupt (C:\FELIPE\BF.FDB)
gbak: ERROR:    wrong page type
gbak: ERROR:    page 4790 is of wrong type (expected 3, found 0)
gbak:Exiting before completion due to errors

ja renomeei varias vezes o arquivo, derrubei conexao e tudo mais.

estou usando o firebird 2.5
se for possivel a ajuda fico imensamente grato.
segue link do banco
http://www.megaupload.com/?d=Y5X1UIUY