git+ssh hangs processing repository

Sometimes there are errors in log:

fisheye IndexingPingRequest-doRequest - Exception during FishEye Incremental Indexing of Gitlab.PreRecieveHook: com.cenqua.fisheye.config.ConfigException: Unable to fetch from remote repository: git@192.168.1.100:some/repo.git
[, fatal: Could not read from remote repository., , Please make sure you have the correct access rights, and the repository exists.]

Error occurs when no action is done in Fisheye or git repository server.
Repository exists, fisheye has access to it (private key uploaded and stored in folder “FISHEYE_INST\data\auth” - fisheye process has access to that folder).

In Windows task manager there are running git.exe and ssh.exe processes. After killing git/ssh processes Fisheye is starting new ones and everything works fine.