After seeing post after post on various security / computer forums where people are stating their task manager No Longer works, I decide to look around. I first suspected a virus disabling the Task manager to hide it's process from the user. Little did I know, it would be verified. So if you have this problem, it isn't your only problem. You more than likely have a Virus or some type of Malware.
This is Not a fix, It is a possible Reason.
Windows XP SP2 Taskmgr bug
Back in 2006 Izee of the EOF virus writing team discovered a possibility to crash the Windows Taskmanager. It was easily done by setting a REG_BINARY value in the Registry of Windows to 0x00. The key is the following:
If you set it to 0x00, 0x00, 0x00... the Taskmanager will crash on the next startup. I (skyout) have therefore coded an exploit and used it back in 2006 in one of my first viruses as a very basic technique to hide my process to the user. Then we waited for a long time without using this bug anymore. With the release of Windows Vista we tested it again and it was fixed. In 2008 now, exactly in February, I got in contact with Microsoft Germany and informed them about the bug. They told me, that they will work on it, but for weeks not even an email came back. Now it is time for making this public! Now this bug is open for every person and everyone can use it and put pressure on Microsoft to fix it.
Here you can find the exploit: [taskmgr_dos.c.txt]