I was also having the same issues, please you do not have to re-install. All you need to do is follow these simple steps:
1. Click on site administration (assuming you are logged as an administrator) under Administrator
2.Select "server"
3.Click on "Session Handling"
4.Under Timeout, adjust Timeout to 2hours or 4hours as the case may be
Sessiontimeout
You see, the problem is actually a session problem.
Enjoy.