dllhost.exe

There is something strange going on in my PC since I have reinstalled it . a dllhost.exe process is automatically starting and its Consuming hell hot of memory. Some times Whenever PC lags I close it instantly .. but sometimes When im watching movie PC goes Blackscreen and dosent respond...

Can anybody please tell me what is dllhost.exe (COM Surrogate). Lately , I have noticed it is using huge amount of RAM like 5-6 GB . When I restart the problem is gone . It appears occasionally , Today It reached to 7GB RAM usage and I got a notification from windows telling me to close programs...