Hi,
I have the same issue with vmware ESX 5.5 U1, Centos 6.5 (up to date) and VEEAM Backup (7.0 R2 - 7.0.0.871).
When veeam do a snapshot with quiesce option the VM is freezed. It respond to ping but we can't login, as if the filesystem was freezed but not released. I have several vm with the same version of vmware tools (provided from vmware repository : vmware repos) and there is no error.
When I do a manual snapshot with the option "quiesce file system" the snapshot success.
Edit : When I do a manual snapshot WITHOUT "quiesce file system" the vm crash.
Did you solved your issue?