It sounds like you are able to play now by running the Client.exe? If so, that's great. If you want to continue troubleshooting the issue with the launcher I would suggest running Procmon. Are you familiar with this utility? Here is a simplified tutorial on how to trouble shoot issues with it:
http://www.howtogeek.com/school/sysi...o/lesson5/all/
(I would scroll down to the "Troubleshooting Problems with Process Monitor" section)
Its a great utility to see what all is going on and help you identify if its permissions accessing a file or what is the culprit.
Hope this helps,
H
/Edit to add - Also permissions are an interesting thing.. Just because someone is Owner doesn't mean everything is 'good'. if somehow an explicit deny got added it overrides all allows. They can be difficult to find sometimes and I have seen applications set deny on files/folders. I would manually review the permissions and look for any deny setting.... but I would investigate with Procmon before anything else as it is your best chance to see whats going on.