ADB not responding. You can wait more, or kill "adb.exe" ... windows 8

When I try to test my Android application with an android emulator as always I now suddenly get an error message. I'm working with Windows 8. So far I tried the following things which unfortunately could not solve the problem:

reinstalling eclipse with android adt
reinstalling java
installing "android studios" first solved the problem but after one day mysteriously also here adb, stopped working with the error message given in the title " ADB not responding ...

furthermore I unsuccessfully tried out some advice from Mr. Google:

Stopping adb.exe via task-manager and restarting eclipse / android studios
"adb kill-server" then "start-server" via command prompt
setting the path to adb.exe as an environment variable
switching off any antivirus or firewall
starting the IDEs as an administrator
updating the IDEs

The only thing I can remember doing which may have destroyed adb on my computer for all times: I connected my motorola smartphone to my laptop and installed the motorola usb drivers but as I said the adb also won't work with the emulator.

Any help would be kindly appreciated. The issue bothers me for more than an entire day now. Maybe someone had similar problems on Windows 8 ?

Solution

Meanwhile the emulator is working again. I cannot definetly say what solved the problem. What It could be a combination of two things:

Deleting the hidden ".android" folder under C:\Users... (Probably there was some malfunctioning automatically created code)
Deleting and recreating the Path variable to the folder with adb.exe ( ...\sdk\platform-tools\;)

Finally it could be a Windows 8 issue which I don't understand.