PSUNMain.exe is a legitimate process, which is a part of the Panda Cloud Antivirus software. It is designed to protect the system. It is not the essential part of the system, so it’s safe to kill it; however, Panda Cloud Antivirus software's work depends on it.
Nevertheless, you could find some people in the Internet that are complaining about this process. The file PSUNMain.exe is considered a safe file. However, modern parasites can name any file anyhow, including this legitimate process name – PSUNMain.exe. If it’s this case, PSUNMain.exe can be malicious. 2-spyware.com research team does not have any information about PSUNMain.exe exploits yet.
If you have problems with this process, if it takes a lot of RAM or CPU, you might be infected with viruses or spyware. In this case, it is best to scan your computer with a reputable anti-spyware software. We recommend using Reimage, it will scan your system and delete every virus or parasite you have there.