Single Application reports that an instance is running, even though it is not.

Single Application may report that an instance of an application is running, even though it is not, when it does not have sufficient access rights to manipulate the lock file.

How to reproduce:

1. Execute the attached example once as a user with admin rights - it will create a lock file under C:\Temp ( or wherever %TMP% points to ) named something like qtsingleapplication-5e9b-0-lockfile.
2. Log out and log in as a user without admin rights. Now execute the example again in a debugger.
3. You can see the warning "QtLockedFile::lock(): file is not opened", the program tries to access the locked file created in step 1, but does not have sufficient access rights. QtSingleApplication::isRunning() returns true in this case.

This doesn't seem to be an issue under Windows 7, since there each user has its own, separate temp folder