This looks like a problem that is fixed with a known issues update for PowerStore 3. On the download page for PowerStore 3 in the known issues section download the update for:
PowerStore 3: Support Fix - Browser error when installing or changing store name (8 Kb)
After you download it read the read me file and follow the directions there to update the site. Once you have done this try browsing to your admin area again to see if the issue is still present. If it is then you may want to try installing the PowerStore again by deleting the files and re-uploading them. Post back and let us know the result you are getting.