Recently, my LAN connection turns Disabled by default any time I restart (or shut down and startup). I had to turn it Enable manually, which is annoying .
The OS is Windows 7. I had no such a problem till, due to an unexpected general electric power collapse, the computer was forced to shut down in the middle of the activity.
After several days I saw that, in fact, the LAN connection was the very last task performed by the OS on start up. What has unenlightened me was the fact that Win7 shows no "waiting circle mouse trail" during that process, which made me think the start up operation was ready, while it was not.