Perl Bulk88, it is not the problem with the perl we are using, we can switch back and forth once we remove the HKLM Perl from the Registry Editor. Everyone in our office lab are using Strawberry Perl, they all have Active perl too. They too switch back and forth. Seems to be, my machine is a peculiar one. I have inquired my co-workers too if they are experiencing this kind of the problem. They have no issues. Please suggest me which one is right. I am ready to do whatever is good for the programs to be executed as I have explained in the previous post.