What is PD91AgentS1.exe?

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the PD91AgentS1.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

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PD91AgentS1.exe file information

The process known as PD91AgentS1 Module belongs to software PerfectDisk (version 2008) by Raxco Software (

Description: PD91AgentS1.exe is not essential for the Windows OS and causes relatively few problems. PD91AgentS1.exe is located in a subfolder of "C:\Program Files". Known file sizes on Windows 10/8/7/XP are 66,824 bytes (75% of all occurrences) or 72,456 bytes. 
The program is not visible. PD91AgentS1.exe is a Verisign signed file. The PD91AgentS1.exe file is certified by a trustworthy company. The file is not a Windows system file. Therefore the technical security rating is 18% dangerous.

Uninstalling this variant: You can also uninstall the associated program (Start > Control Panel > Uninstall a Program > PerfectDisk 2008).

Recommended: Identify PD91AgentS1.exe related errors

Important: Some malware camouflages itself as PD91AgentS1.exe, particularly when located in the C:\Windows or C:\Windows\System32 folder. Therefore, you should check the PD91AgentS1.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


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Best practices for resolving PD91AgentS1 issues

A clean and tidy computer is the key requirement for avoiding problems with PD91AgentS1. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the PD91AgentS1.exe process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

PD91AgentS1.exe [all]