sk hit the nail on the head. The start command appears to have problems with paths that contain spaces, even if you quote them. However, I have found that it you quote the individual element of the path that contains the space, it then works.

So, for the path c:\program files\junk.txt, if you issue the command

system 'start', '"c:\program files\junk.txt"';
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it fails, but if you issue the command

system 'start', 'C:\"program files"\junk.txt';
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It succeeds. So you would need to modify your quoting mechanism to be something like this (untested):

sub logfile{
        my $file = "$gGui{complogpath}/$gGui{complog}.txt";
        my @args = ("start",$file);
        for (@args) {
            s[ 
                ( [\\/] )               ## A path delimiter
                ( [^\\/]* \s [\\/]* )   ## Two or more non delimiters 
                                        ## including a space
                ( [\\/] )               ## Another delimiter
            ][$1"$2"$3]gx;              ## Quote the path element
        };
        system(@args) == 0
          or warn "Couldn't launch '$file' : $!/$?/$^E";
}#logfile
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