weird problem : "No such file or directory " of rhtml file on rails

I found a few errors in my production log like this below


ActionView::TemplateError : No such file or directory - /
In app/views/layouts/simple_html.rhtml


It's so weird because the error was happend in the file it said "no
such file or directory". Our site has about 500 thousand pageviews 1
day now , and this error happend (2-200) times one day, mostly it is
layout file, I can't reproduce it in my testing , I just heard the
complaint from 2 guests and found it in log.

Our environment is
"lighttpd 1.4.16 , ruby 1.8.6 , rails 1.2.3, fastcgi , production"
Maybe It happend when rails try to reloading the rhtml files, Can I
disable the automatic reloading of rhtml files in rails view in
produciont environment ? or have anyone met this problem before?