Ilya,
Have you tried Microsoft Security Essentials 1.0 yet? I tried it it with DefenseWall and had a problem with MSE announcing once in a while that it had been turned off. Disabling DefenseWall seemed to fix that problem. It could be something else causing this but the only other security feature I run is SRP. MSE disables Windows Defender upon install.

This is in Windows 7 with the Iron browser by the way.

Just a for your information post.

I'm sure someone else will chime in on this subject.

Later...

I did not see this behaviour when the two programs were installed but I did see occasional freezes of "Morro" and high CPU time/memory usage of the Antimalware Service Executable, MsMpEng.

But not surprising since this is pre-beta software. Uninstalled Morro after a few hours of use/testing.

Will be of interest if the version released tomorrow is the same or an update.

Running MSE with Defensewall on Vista Home Premium SP2, I also saw MSE report real time protection turn off and back on several times. Without Defensewall MSE real time protection stays solidly on.

With both MSE and Defensewall turned on, there is a significant delay of web pages opening using IE8. Turn off defensewall and this delay of IE8 goes away.

Using Firefox 3.5 RC2 with both MSE and Defensewall on, there is no delay.

Have tried MSE in several different snapshots with DW, OA, Outpost and Zemana - one only in each of the four different snapshots and MSE froze the machine and locked up in all of them after a while. Wouldn't work at all with Zemana which left me with the conclusion that it is allergic to HIPS based programs. Will probably give it another go later as it is after all a Beta

If you encounter any problems with pre-beta software, report to its support service.

While I don't use DefenseWall, I've also experienced that behavior with MSE. I believe it turns it self off (perhaps a bug??? It has got to be!!!) when there's high CPU usage. It happened once. I was doing some work, and CPU usage went like crazy for a while, and after a few seconds, MSE turned off.

Interesting, after first installing 2.56 I continued to see significant delay when opening and browsing on IE8 with Microsoft Security Essentials also active with real time protection. If I turned off MSE real time flie and program detection off, the delays went away.

Today I turned back on MSE file and program detection with Defensewall and all delays have disappeared. Also tried with Sandboxie, MSE and Defensewall and no delays appear on Vista Home Premium SP2.

Not able to determine a reason but...

I have sent a report to MS Software Compatibility center- hope, this will help to remove all the problems in the future.