> mingw32 version is almost equal to mswin32.  Could you test
> with it?

Hi again Nobu,

Here is the trace from running under mingw32:

I:\mingw-ruby\bin>ruby audiotron-play-watcher.rb
0
Playing track 0 of 21119 in a random way
(05) Wherever I May Roam.Mp3 by  on  is 391 seconds long
File is :- \\CLEMFAR\bigmusic (Z)\collections\from someone at work\(05) 
Wherever
  I May Roam.Mp3
1
2
3
4
5
6
7
I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:501:in `sysread': Bad file 
descriptor (Errno::EBADF)
from I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:501:in `rbuf_fill'
from I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:443:in `read'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:1552:in `read_chunked'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:1525:in `read_body_0'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:1508:in `body'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:1494:in `reading_body'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:811:in `request'
from audiotron-play-watcher.rb:37
from audiotron-play-watcher.rb:36:in `start'
from audiotron-play-watcher.rb:36

I:\mingw-ruby\bin>

It appears to have the same problem as the mswin32 version a second run 
also crashed out, but ran for 32 iterations. A third run also dropped 
out quickly, this time with the error

I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:501:in `sysread': Invalid 
argument (Errno::EINVAL)
from I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:501:in `rbuf_fill'
from I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:477:in `readuntil'
from I:/mingw-ruby/lib/ruby/1.7/net/protocol.rb:488:in `readline'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:1406:in `read_status_line'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:1390:in `read_new'
from I:/mingw-ruby/lib/ruby/1.7/net/http.rb:809:in `request'
from audiotron-play-watcher.rb:37
from audiotron-play-watcher.rb:36:in `start'
from audiotron-play-watcher.rb:36

Rob