I've not used IO::All at all, but, some things to try.. print that $temp_file with Data::Dumper, and see what it contains (Im guessing undef, or some value thats supposed to be the filehandle thats undef). 
$VAR1 = bless( \*Symbol::GEN0, 'IO::All::Temp' );

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Try setting PERLDB_OPTS='NonStop frame=1 AutoTrace LineInfo=tperl.out' (as an environment variable), and running it using perl -d (then read the resulting tperl.out) ?
This was pretty cool to see. Thanks for the idea! I've never played much with Perl's debugging features, but it's cool to see the extensive support provided. However, the output is difficult to comprehend. It would probably be easier to follow if I was familiar with the source of IO::All; especially if I knew why and when each sub was executed.
Also, you didn't mention what system/perl/IO::All versions you're using.. 
$ uname -a
Linux mikey.emperorlinux.com 2.4.24-emp_2424sw #1 Fri Feb 20 17:56:50 
+EST 2004 i686 i686 i386 GNU/Linux

$ perl -v
This is perl, v5.8.3 built for i386-linux-thread-multi

$ perldoc -m IO::All | grep VERSION
our $VERSION = '0.31';

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(snipped for brevity)

---
"A Jedi uses the Force for knowledge and defense, never for attack."

In reply to Re^2: IO::All and temporary files by meonkeys
in thread IO::All and temporary files by meonkeys

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