Task Manager Issue

[TavoxPeru 0]

If you are not administrator, you wouldn't be able to change anything in regedit in the first place for all Windows after Windows 9x. This holds especially true on Windows Vista since the User Account Control will actually stop you and ask for an administrator password before you can even see the regedit.
It also depends on the administrator, maybe the environment allows users to kill off software that may be clogging up the system but don't allow them to use the regedit.

If it's something that a virus has caused, then obviously the regedit is available (unless that virus also blocked regedit access then you're screwed). Else, as you said, the regedit is access denied.

xboxrulz

I agree, and as i said before a lot of viruses do exactly this thing blocking the task manager and the registry editor. The following registry code will unlock the Registry Editor globally for the machine and for the current user:

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
"DisableRegistryTools"=dword:00000000

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System]
"DisableRegistryTools"=dword:00000000

To lock them, simply set the values to one (1).

Best regards,

[iGuest 3]

Hi, I had the same problem few days back and got it resolved. The problem is happening because the task manager is running in the Tiny footprint mode. More information is available in Microsoft support page :-https://support.microsoft.com/en-us/kb/193050

-reply by sabs