Subject Running gfix and gbak from windows service

We using both gfix and gbak from windows service to perform routine maintenance operations

such as moving db to shutdown mode performing check and then backup then online mode

This works fine on Firebird 2.5.2 however it does not work on 2.5.3 & 2.5.4

The gfix or gbak just start running then hangs for hours doing nothing till I terminate the process  

The problem seems to exists on windows 7 & 8.1 don't know about other OS's 

I tried running the service using user account instead of the system account but it did not help

Does anyone has a suggestion or work around ?