I just recently started using Microsoft Security Essentials as an anti-spyware, anti-malware solution. It’s free from Microsoft and I’ve read a few positive reviews that said it was worth using and worked well. Here’s what I’ve experienced so far and I’d like your input if you have any ideas or opinions.

I removed my Symantec Antivirus and installed Microsoft Security Essentials (MSE). My system locked up. Hard.  Not to be easily beaten, I rebooted and everything worked as it should.

MSE uses about 66MB of RAM while running on my PC, which is comparable to my prior AV software, so I am pretty pleased in that regard. In addition to the real-time monitoring component, scans can be scheduled to run daily or weekly and at a set time of the day or night. You are also presented the option to check for software updates prior to scanning.

I have encountered two different problems with MSE. More than half of the time, when I attempt to download something with Firefox, MSE will take all the CPU time while the download is in progress. Any applications in the foreground hang and the only way to relieve the problem is turn off the MSE realtime protection until the download completes. It’s annoying, but I can live with it, since it’s predictable.

The second problem occured on a different systemI use for games. I have repeated problems with msmpeng.exe chokes my games while they are running. Even with realtime protection turned off, the executable consumes over 65% of the CPU time while my games are running. Oddly, even after I have excluded the folder containing the games and their executable, it still happens. Until Microsoft gets this resolved, I have removed it from the system.

What are your experiences? Has the CPU hogging happened to you? If so, were you able to resolve it?