Your computers comes to standstill all of a sudden it has got a antivirus too whats the problem then?

When your computer freezes all of a sudden (no mouse response, no keyboard response, no response to CTRL-ALT-DEL on a Windows system) then it is most likely that something's wrong with your computer hardware (ie. physical devices). This should be determined by an expert (who needs to test all components, like memory etc.). These kind of problems can occur regardless of the software programs you're running. Another possibility however is a software issue. On Windows systems this can be determined by booting into safe mode (pressing F8 during start up). If the problem doesn't occur in safe mode, then you can start to determin what program or function causes the crash.