I ran into a case where a developer was having issues with the Oracle driver packaged with CF. This is a known issue and the workaround is to move back to the U3+ drivers. After following replacing the macromedia_drivers.jar in JRun4\lib the problem still exhibited itself so the thought was that the drivers did not fix the problem. My thought was that the problematic drivers were still being loaded from some other location. There is an easy way to determine this in ColdFusion using the Java API. Here is the code:
<cffunction name="resolveResource" returnType="string">
<cfset var resourceURL = getClass().getClassLoader().getResource(resource)>
<cfreturn "could not resolve resource">
This code will return the location of the Jar file that is loading the class, and it output the following on my machine:
macromedia/jdbc/oracle/OracleDriver.class: [ jar:file:/C:/JRun4/servers/latestcfbuild/cfusion/WEB-INF/cfusion/lib/macromedia_drivers.jar!/macromedia/jdbc/oracle/OracleDriver.class]
This told me that the drivers were being loaded from another location and they needed to update that Jar instead.