In Exchange 2010 event logs referring to user mailboxes tend to be in the format of GUID, this makes it a little difficult in troubleshooting and identifying a problematic mailbox. In exchange it is very simple to translate the GUID to display name in powershell.
Copy the GUID in the event ID and copy into powershell:
get-mailboxstatistics -Identity <GUID> | fl
You can just as easily use:
get-mailbox -Identity <GUID> | fl
However the output list is very extensive and it will take some time to locate displayname.
There are a number of articles on how to convert the GUID via script to retrieve the display name, but the line above does the job extremely quickly especially if you use copy and paste with the GUID.