task manager won't run windows after Ctrl+Alt+Delete

I'm running Windows XP 64-Bit Edition, this problem has started happening today.

When I press Ctrl+Alt+Delete I get the Windows Security Dialog box, but when I click the Task Manager button, nothing happens.

It first started happening earlier today. My machine was running slow so I brought up taskmgr to see if there was a process eating up resources. Task manager opened and then it locked up. I tried Ctrl-Alt_deleting again, but I was unable to start the task manager from clicking the Task Manager button. I tried going to the system32 folder under windows to run it directly. No luck. when I do that Windows reports that it can't find the file, even though I can see it in the folder. I launced Process Explorer from SysInternals but I can't see anything suspicious there.

I've gone through the steps in the Malware guide and I'm still having the issue. I'm running Avast Professional 4.8 but nothing has popped up.

I'm attaching the logs from my clean up exercises. Since I'm running 64-bit I only have three files to upload.

 

Issue fixed:

I was able to track down the corrupted registry entry with JV16 Power tools 2009. Once I cleaned up the bad registry entries and reboot the system runs fine.

In addition, I removed Java and Quicktime and installed the latest version instead of depending on the in-application update feature.

I removed Avast and went with Kapersky on this machine. Thanks for all the other help others have provided that gave me insight.