When I double clicked the quickstart.jar it is getting stuck in middle and I am seeing below error in stderr.log. I am using Java 1.6.
Error - "Can't load http root property: java.io.FileNotFoundException: C:\Adobe_CQ5\Author\crx-quickstart\conf\sling.properties (The system cannot find the file specified)"
Can you use jar file name -unpack and then start using start script or using jar ?
I also had the same error. I ignored it for few mins and CQ5 was able to come up in few mins without any issues. Not ideal but seems to work