It's not Perl but some module. But as you don't show anything of your code, it's kinda hard to diagnose. Possibly it has something to do with Apache::Registry, at least in its source code, there is mention of ::ROOT. If you crank up the debugging output for Apache::Registry to at least 4, you will see the steps it does. I see an mtime check there, so maybe your mod_perl scripts are accessed via NFS and the server times are off, so the scripts get recompiled all the time?

I don't see any code that appends X to the package name, so maybe your problem lies elsewhere. Reduce your code until you have a minimal, self-contained example that you can show us.