If you allow users to access the site from both
www.yoursite.com and yoursite.com, then you will have this issue.
Questions/Problems regarding modifications/styles need to be asked in the modification/style thread. That is where the support for modification/style is - not out here in the main forums. Please note that if a modification/style is unsupported (or even if it says it is supported), you may be on your own if you chose to install it.