I've been trying to solve this same problem,and I just found a solution which works for me:
@First i saw a file named adb_has_moved.txt.The contents of the file were
"The adb tool has moved to platform-tools/
If you don't see this directory in your SDK,
launch the SDK and AVD Manager (execute the android tool)
and install "Android SDK Platform-tools"
Please also update your PATH environment variable to
include the platform-tools/ directory, so you can
execute adb from any location.
"
so i copied adb.exe from platform-tools to tools......BUT THAT DIDN'T WORKED OUT
Then i tried the next solution that is to create a new device bt that also flopped
removing old virtual devices and creating new one was also not working for me
SO i tried the solution below and stated by many.i found it from a spanish blog.i dont knw spanish bt i do knw google translate.
It seems the problem is the spaces in the path for example:C:\Program Files\Android\android-sdk
CHANGE THIS TO
C:\PROGRA~1\Android\android-sdk
It really worked out for me.