Sorry for the extremely long blog title, but this is an error that I have come across recently, and wanted to share the solution.

<em>Freezing guest operating system
CreateSnapshot failed, vmRef "*", timeout "1800000", snName "VEEAM BACKUP TEMPORARY SNAPSHOT", snDescription "Please do not delete this snapshot. It is being used by Veeam Backup.", memory "False", quiesce "False"
File &lt;unspecified filename&gt; is larger than the maximum size supported by datastore '&lt;unspecified datastore&gt;</em>

The solution is actually to move the configuration files from from a datastore that has a lower block size (2MB or 4MB) to a datastore with a larger block size.  This is due to the fact that the expansion of the data during the backup process.