This is in relation to the article explaining slow logon times and system crashing when logging off due to a duplication of outlook files into Prf*.tmp files

Original Microsoft article:

SYMPTOMS
Your roaming profile may accumulate extra files named Prf*.tmp, and the following error message may be logged in the Application event log:
Event Type: Error
Event Source: Userenv
Event Category: None
Event ID: 1000
Date: date
Time: time of day
User: S-1-5-21-#########-##########-##########-####
Computer: Computername

Description:
Windows cannot copy file \servernameshare…Prf???.tmp to location R:Documents and Settings…Prf???.tmp. Contact your network administrator.
DETAIL – Cannot create a file when that file already exists.

CAUSE
This problem may occur if the Indexing service or some other process (such as an open file agent) has opened the indicated temporary file during profile synchronization. If so, the temporary file is not deleted. It is uploaded with the roaming profile when you log off and reconciled to the local profile when you log on again.

Although antivirus software may also cause this problem, the impact is likely to be minimal because there are fewer file operations for such processes than for Indexing and open file agents.

RESOLUTION
To work around this problem, use either of the following methods:
•    Turn off the software or the service that is in conflict with the profile engine.

-or-
•    Exclude profile folders from the conflicting operational scan or monitor functionality.
Microsoft recommends that you examine any files before you delete them to make sure that they do not contain useful data. The profile engine specifically does not delete littered Prf*.tmp files to prevent potential data loss.

To disable shared folder caching:

1. Right-click the folder for which you want to disable caching, and select Properties.
2. On the Sharing tab, click the Caching button.
3. Deselect the Allow Caching Of Files In This Shared Folder option, and click OK.
4. Close the Properties dialog box.

Article written by MyComputerAid.com