Why do we suspect anything new?

A couple of weeks ago, I was trying to use Jython with JasperReports. Jython kept ignoring the classpath.

I suspected the beta version of Jython and then JDK 6. Only then, I noticed that the jython shell script in the distribution specifically manipulated the classpath.

Even if I am the only user, I prefer to install any application in a common location, like /usr/local. This also created a problem for jython. It couldn't create a cache directory and failed to find the required classes even though they were available on the classpath. Should't jython create the cache directory in the user's home?

I still can't understand why do we overlook signs of problems and suspect anything new.