It seems like every time my system bogs down and becomes unresponsive, Task Manager shows MsMpEng sucking up 50% of my CPU.
I am using Microsoft Security Essentials antivirus on my Pentium 4 PC running Windows XP Pro SP3. Occasionally my PC seems to stall. For example, right now I have run a file search, and have a "Search Results" window open with about 250 files listed. Every time I try to scroll the window (drag the scroll bar), my system just hangs for 15 - 30 seconds. I've found that when this happens, MsMpEng.exe process has sucked up 50% of my CPU cycles, and nothing else can run. What is MsMpEng doing, and why does it do it every time I try to scroll this window?