99% CPU usage CIS + Windows Defender

Background: I’ve been testing CIS out and have been overall pleased.

Had one very alarming problem this last week: appears to be conflict between CIS and Windows Defender, although I’m open to it being something else.

Fast laptop 2 GB Memory.
Memory and hard disk are known-good. I tested them several weeks ago.
Clean OEM install of XP Pro SP3 several weeks ago.
Installed Microsoft Windows Defender, Microsoft Office 2003 Professional OEM, Accountable2You Internet Accountability Software, and e-Sword.
Installed CIS 3.12.111745.560 shortly afterward (when v3.12 was released).
No firewall, just installed the antivirus and defense+.
No other antivirus/antimalware applications installed.
My account has full administrator privileges.

Last week, I was awake early, journaling and reading the Bible. I journal in Microsoft Word.
Open & active applications: Microsoft Word.
Open processes in background: CIS, Accountable2You, Windows Defender.
I opened e-Sword and the system hung. It took me 15 minute, no exaggeration, for CTRL+ALT+DLT to bring up Task Manager. cmdagent.exe was at 100% CPU, about 16,000k memory. Unable to kill cmdagent.exe.

I have used Word + e-Sword (with CIS and Windows Defender) for several weeks, daily, with no problems.

After 35 minutes of attempting various things (mostly waiting), I noticed that right-clicking on the Windows Defender icon and choosing Exit made cmdagent.exe release the 99% GRIP of the processor, and drop down to normal.

Rebooted… immediately cmdagent.exe is back at 99% of processor. Tried waiting it out… nope. It is not doing a scan, nor is Windows Defender. I set AntiVirus to disabled and Defense+ to disabled…no change. I set Windows Defender / options to NO real-time protection. No effect. Left these settings in effect. Had to force power-off laptop as it finally became unresponsive.

Rebooted… immediately cmdagent.exe is back at 99% of processor. Reviewed CIS logs … nothing suspicious noted except when I tried to kill cmdagent.exe process using taskmanager. Disabling the processes behind Accountable2You made no effect. It’s already a clean system, but I got aggressive and killed all non-core XP processes and it still was bogged down. When you kill Windows Defender at the process level, it restarts itself of course. But right-clicking on Windows Defender tray icon and choosing Exit works, and causes cmdagent.exe to release its tight grip on processor and act normal.

Rebooted several more time and tried several other options. Most times I had to force off processor as the system became nearly unresponsive to the point that task manager did not come up, window stopped refreshing, etc.

In Safe Mode I set the CIS service to startup type DISABLED. Rebooted into normal mode. Laptop is fine and runs great. Noticed that cmdagent.exe is not running.

Tried uninstalling Windows Defender and enabling CIS… no problems. Re-installed Windows Defender (with real-time protection disabled) and enabled CIS… CIS grabs 99% processor (with stateful A/V scanning).

Summary: appears to be a conflict between CIS and Microsoft Windows Defender. Any potential resolution or suggestions?

Please read here


That’s it Dennis – deleting /scanners/bases.cav and replacing with the /repair/bases.cav in safe mode fixed the problem. Thanks. Running fine with Windows Defender again.

Yikes, this was a major problem. Then again, AVG is infamous for deleting a required Microsoft Windows file from /system32/ some time ago. Everyone makes mistakes including me.

Thanks for the free program Comodo. Aside from this issue and a some false positives, I’ve been very pleased with the quality of CIS.