crsss.exe is a process which is registered as W32.Rbot.mx Worm.
"This virus is distributed via the Internet through e-mail and comes in the form of an e-mail message, in the hopes that you open its hostile attachment. "
The worm has it's own SMTP engine
Non-system processes like crsss.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that your registry has suffered fragmentation and accumulated invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues