I have the same problem but when I try to browse my service at browser, I get an exception:
Memory gates checking failed because the free memory (134033408 bytes) is less than 5% of total memory. As a result, the service will not be available for incoming requests. To resolve this, either reduce the load on the machine or adjust the value of minFreeMemoryPercentageToActivateService on the serviceHostingEnvironment config element.
I close some programs, change 'mex' service path to absolute and service starts work properly.