I had an issue that when typing reboot, or pressing the reset button, the Yun (open wrt) would not correctly reboot (e.g. the white LED did no go on anymore). The only way the reboot worked correctly was by power cycling the device. Also a watchdog based reboot didnt work.
Cause: my running sketch was sending stuff to the Console. This will interrupt the boot. The "old" Uboot version will be interrupted by any char. A bridge operation will cause the same problem (I think even a get as this is implemented as transfer)
- newer uboot version (with openwrt-yun 1.3) is more strict and will only interrupt on the characters "ard". The upgrade is unfortunatley a manual step that will void warranty. See http://arduino.cc/en/Tutorial/YunUBootReflash (you can do only the uboot stuff)
extra info: takes about 4sec to enter uboot (so probably a good idea to let a sketch do nothing the 4 first seconds)