Aha! This looks like a similar problem to my own... I'm a relative beginner when it comes to inheritance, so I'm sure that's where my problem lies. Here's what I'm doing: I have a class, "class_X", which is a subclass of DBI, and another class, "class_Y", which is a subclass of class_X. class_X is fairly generic, and merely extends some of the DBI functionality; class_Y is more specific to my database needs. Here's some relevant code:

package class_X;
require DBI;
@ISA = qw( DBI );
sub new {
     my( $class, $dns, $username, $password ) = @_;
     my %attr = ( PrintError => 1, RaiseError => 0, AutoCommit => 1 );
     my $self = DBI->connect( $dns, $username, $password, \%attr ) or 
+return;
     push @ISA, ref $self if( not grep { $_ eq ref $self } @ISA );
     return bless $self, $class;
}

sub DESTROY {
     my( $self ) = @_;
     $self->disconnect;
}
1;

package class_Y;
require class_X;
@ISA = qw( class_X );

sub new {
     my( $class ) = @_;
     my $dns = "DBI:mysql:database=XXX";
     my $user = "XXX";
     my $pwd = "XXX";
     my $self = class_X->new( $dns, $user, $pwd );
     return bless $self, $class;
}

sub DESTROY {
     my( $self ) = @_;
     $self->disconnect;
}
1;
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This used to work fine (before upgrading DBI); now I'm having the same problem as mentioned in the links you (so graciously) forwarded.

I haven't yet been able to wrap my brain around the problem and figure out exactly how to solve it... Any friendly nudges in the right direction?