Convert who.dat from version 0.003 beta1, beta2 or beta3 to
WHO version 0.004 beta1 :

CAUTION! Do not run 'convert.exe' if you work with v0.003 beta5 or v0.004 beta1.

Place convert.exe in the same directory where the file who.dat is
placed. Then backup the file who.dat, only for secure.

Then start convert.exe, if there is no error-message, everything went ok.

If there is any error, please use the old version of WHO and send me
an email, i'll try to help.

After converting to the new mask, you can delete the files 'convert.*' 
and 'caution.now'.

That's it. Happy working ;)