mod_rewrite not working in .htaccess.

i am using xampp on windows.For last two days i am trying to rewrite URL's
but mod rewrite is doing nothing.its taking me to the same page.i am trying
to do a simple redirect from foo.html to bar.html as its is a n example
rewrite docs. I have put all the directives in .htaccess.

.htaccess is processing cause adding something like "blah blah blah" in it
results in 500 internal server error. here are lines in my .htaccess file.

RewriteEngine On
RewriteRule ^/foo.html /bar.html [R]*

I enabled logging and here is what it is telling me for my last request for
foo.html at trace3.

trace3] [pid 5116:tid 8]
mod_rewrite.c(475): [client 127.0.0.1:4656] 127.0.0.1 - -
[localhost/sid#9006d0][rid#9dd270/initial] [perdir D:/x3/htdocs/] strip
per-dir prefix: D:/x3/htdocs/foo.html -> foo.html

trace3] [pid 5116:tid 8]
mod_rewrite.c(475): [client 127.0.0.1:4656] 127.0.0.1 - -
[localhost/sid#9006d0][rid#9dd270/initial] [perdir D:/x3/htdocs/] applying
pattern '^/foo.html' to uri 'foo.html'

trace1] [pid 5116:tid 8]
mod_rewrite.c(475): [client 127.0.0.1:4656] 127.0.0.1 - -
[localhost/sid#9006d0][rid#9dd270/initial] [perdir D:/x3/htdocs/] pass
through D:/x3/htdocs/foo.html

trace3] [pid 5116:tid 8]
mod_rewrite.c(475): [client 127.0.0.1:4656] 127.0.0.1 - -
[localhost/sid#9006d0][rid#55020a8/initial] [perdir D:/x3/htdocs/] strip
per-dir prefix: D:/x3/htdocs/favicon.ico -> favicon.ico

trace3] [pid 5116:tid 8]
mod_rewrite.c(475): [client 127.0.0.1:4656] 127.0.0.1 - -
[localhost/sid#9006d0][rid#55020a8/initial] [perdir D:/x3/htdocs/] applying
pattern '^/foo.html' to uri 'favicon.ico'

trace1] [pid 5116:tid 8]
mod_rewrite.c(475): [client 127.0.0.1:4656] 127.0.0.1 - -
[localhost/sid#9006d0][rid#55020a8/initial] [perdir D:/x3/htdocs/] pass
through D:/x3/htdocs/favicon.ico

*Adding same lines into httpd.conf Works*

i hve been using mod_rewrite in .htaccess but never had such problem
before:(