New-PWDocumentVersion - database deadlock error?

I have a script to synchronize files in a server folder with documents in a ProjectWise folder.   I have several thousands of documents to sync so I have 'powershelled' the task.

One of my commands is to create a new document version:

Get-PWDocumentsBySearch -FolderPath $pwfolder -FileName $theFile  | New-PWDocumentVersion -VersionString $verString | Out-Null

This will happily run for long periods of time, and then fall over for no apparent reason: 

New-PWDocumentVersion : Error changing document 'FILENAME' to new
version. Error creating new version of document.At SCRIPTNAME1:548 char:97
+ ... e $theFile | New-PWDocumentVersion -VersionString $verString | Out-N ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (Version:String) [New-PWDocumentVersion], Exception
+ FullyQualifiedErrorId : ErrorID: Database transaction deadlock error.,PWPS_DAB.NewPWDocumentVersion

What is a database transaction deadlock error and how to prevent it?  For the record, the $verString is set to "P02" and the previous version is "P01".

Thanks for any help.