System Check is a malicious application that imitates actions of a fake system defragmenter, but in fact it is a completely useless program. This badware strongly reminds of System Fix and Data Repair fake system defragmenters which were popular some time ago.
The program gets inside the system with the help of Trojan viruses. These infections make some changes in the targeted system which make System Check to be run automatically with each system reboot. The program imitates performing system scan which ends up stating that your system needs defragmentation. By the very end, the program recommends getting a full version of System Check so it could solve your security issues.
Most probably the program will warn about some hard drive problems of RAM issues even though your system is completely fine. Moreover, it will constantly threaten you by displaying different security notifications and pop up ads which will warn about your had drive problems as well.
Please get rid of System Check as soon as you detect it on your machine. Please do not act the way System Check tells you to act. This is not a program worth your trust.