I think the SshHostKeys are now stored in HKCU\Software\SimonTatham\PuTTY rather than HKCU\Software\FileZillaPo\PuTTY\SshHostKeys & if the connection dialog is cancelled (without accepting the keys) then the file %LOCALAPPDATA%\PUTTY.RND is left behind.
XP SP3 admin, connecting to sourceforge