Git agent side checkout occasionly fails

Hello,

We use Git agent side checkout in our builds, and sometimes build  cannot start on the agent due to 2 different problems:

!!! Unable to collect changes

[09:35:23]: Unable to collect changes

java.util.concurrent.ExecutionException: jetbrains.buildServer.vcs.VcsException:

Problem collecting changes for 'Calculation Module :: Calculation Module 2013.Mar' :

Retrieving current version failed: org.eclipse.jgit.errors.NoRemoteRepositoryException: atum@git.napa.fi:d:/git-repo/calculationmodule.git: 0

[main] bash 155052 exception::handle:

Exception: STATUS_ACCESS_VIOLATION Exception: STATUS_ACCESS_VIOLATION  

Failed to perform checkout on agent:

'"C:\Program Files (x86)\Git\bin\git.exe" fetch --progress origin +refs/heads/model:refs/remotes/origin/model' command failed.

 stderr: 0 [main] bash 78140 exception::handle:

 Exception: STATUS_ACCESS_VIOLATION 437

Such problems  happens 1-2 times/day per agent, and even updating source failing then in the next minute it succeeds on the same agent and for the same repository.

We use agent side check out and Authentication Method is Default private Key connection via SSH. Nothing has been changed in git side at least for a year and problems described above appeared few weeks ago.

Could you please advise how problem can be fixed?

Thank you in advance.

Best regards, Georgiy