Hi.

Can you try latest ruby_1_8 branch?

I can be got from ftp://ftp.ruby-lang.org/pub/ruby/stable-snapshot.tar.gz or
cvs checkout -r ruby_1_8 -d as_you_wish -- ruby

This is summary of changes after 1.8.4.

http://www.atdot.net/~ko1/w3ml/w3ml.cgi/ruby-cvs/msg/16299

    * lib/yaml/rubytypes.rb (Fixnum): Bignum could not be loaded in
      ruby 1.8.3/1.8.4. [ruby-core:6115]
    
    * lib/yaml/rubytypes.rb (Numeric): Subclass of Numeric could not
      be dumped properly. [ruby-core:7047]

http://www.atdot.net/~ko1/w3ml/w3ml.cgi/ruby-cvs/msg/16302

    * ext/syck/rubyext.c (syck_resolver_transfer): should be able to load
      !ruby/object:Bignum syntax 1.8.3 dumped. [ruby-core:6159] (written
      by akira yamada)

http://www.atdot.net/~ko1/w3ml/w3ml.cgi/ruby-cvs/msg/16304

    Sorry, commit miss.

http://www.atdot.net/~ko1/w3ml/w3ml.cgi/ruby-cvs/msg/16326

    * ext/syck/emitter.c (syck_emit_seq, syck_emit_map, syck_emit_item):
      should output complex key mark even if map's key is empty seq/map.
      [ruby-core:7129]

This is my result.

E:\ruby-cvs\win32_1_8>ruby -v
ruby 1.8.4 (2006-01-17) [i386-mswin32]

E:\ruby-cvs\win32_1_8>irb -ryaml
irb(main):001:0> t = Time.now.to_i
=> 1137537149
irb(main):002:0> y t
--- 1137537149
=> nil
irb(main):003:0> t.to_yaml
=> "--- 1137537149\n"
irb(main):004:0> YAML.load(t.to_yaml)
=> 1137537149
irb(main):005:0> y 6
--- 6
=> nil