First turn on warnings with a "use warnings;" right below the "use strict;" in your program.

I'm willing to be that $regDate, $regUserName, $regEmail, $regCountry, $regIp, $regRefer remain undefined the first time through.

I you find a benign reason for the undefined variables, then just skip printing the line:

    next unless defined $regDate;
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Otherwise dig through your code to find the reason.

I wonder what would happen if you increment the offset you're seeking on by 1.

    seek(REGLOG, $offset[0] + 1, 1);
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