I'm having the f***ing same issue on my mid-2010 MBP.
I installed mavericks lately and since then the problem occurs more often. I'm working and all of a sudden, Wifi is disabled and can't be re-enabled without a restart, not very usefull.
Looked in Console.app but could not find a log message related to Wifi or networks...
If anyone have suggestions to understand the problem or how have ideas to share to try to fix it, please help us because I'm pretty sure that we are not the only onew with this problem.
I've been having this exact same problem. I have an early 2011 MBP 13". Sometimes restarting only result in the wi-fi working for a few seconds. I know it's not the wires because I opened up case yesterday and checked all the connections, cleaning everything out. Another forum had suggested it was dust or dirt lifting the ribbon connector of the wi-fi card to the logic board but I cleaned that as well and the problem continues. I'm even tried a fix where you maintain a connection and data transfer by using terminal to continuously ping a website, but while writing this comment that stopped and I am finishing the comment in a text file that I’ll update once I restart my computer to get wi-fi back again. Similarly I know it's not my router because every other device works fine. Have you found anything that helps?
Same issue here. Restarting seems to be the only way to fix it. Nothing in the logs.
When trying to do `sudo ifconfig en1 down`, followed by `sudo ifconfig en1 up`, the system locks up and a hard reboot is the only way out of it. Everything was fine pre mavericks, so I can only assume that it's an OS issue.