Why does adb work only while the tablet boots? I have a Samsung Galaxy Tab.  When I type "adb devices" or "adb shell", it works while the tablet is booting up - showing the Samsung logo or animation - but once the orange lock screen shows, the connection breaks and adb exits.   I've tried unplugging and plugging the USB cable, fiddling with settings and configurations, 

According to answers to other questions I've asked, adb ought to work just fine anytime the tablet is on.  Maybe for others, but not for me.  

Hint: it's not anything to do with udev. I took care of the udev rules thing along ago. Here is my udev rules file:

=&gt; cat /etc/udev/rules.d/80-gtab.rules
# Samsung GT-P7510/Galaxy Tab 10.1
ACTION!="add", GOTO="gtab_rules_end"
SUBSYSTEM!="usb|usb_device", GOTO="gtab_usb_end"
ATTR{idVendor}=="04e8", ATTR{idProduct}=="6860", SYMLINK+="gtab" MODE="777"


I've restarted udev with "cd /etc/init.d ; ./udev restart" (or something similar) and I see /dev/gtab, created by this udev rule.  I've tried other rules that don't involve /dev/gtab, different variations found on the web.  

One time, the app gmtp actually ran, let me see the file system and copy many files, so I know it's possible.  I don't recall exactly what I did to make it happen. But I have been using the exact same udev rule file ever since.

I've been googling and experimenting for over a month now, and except for that one lucky time, haven't gotten adb to work reliably.

Main question:  What are some ways to diagnose this problem of the usb connection breaking when the tablet gets past boot-up?
If you have WiFi access in your place and the tablet is rooted, you can try adbWireless to see if adb runs well in your tablet. If it works then the problem may be your broken usb cable or usb connector.