I'm rather hesitant of whether to "bump" in here, as I'm no more than just a random computer user, and no expert whatsoever, at all. The reason I normally come to the forum myself is to search for info or ask for help too.

Thus I apologise in advance if I'll add nonsense in any way. (Or if my post is unsuitable, please do remove it, and thank you at once for your understanding.) Yet, if somehow helpful to come to resolve this case, I thought I'd add my "experience" with having Task Manager inaccessible (nothing would happen when pressing CTRL+ALT+DEL either):
In my case it resulted from an infection as described by this ThreatExpert report:
http://www.threatexpert.com/report.aspx?md...f19102ffc0db9deFrom what I figured from what I read by then, this was the culprit of Task Manager not being accessible, this registry setting newly created by that infection:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe]
"Debugger"="0"
As I understand it, let's say that "hijacked" the execution of Task Manager (in this case, not to execute any other specific program instead, but rather to simply block the execution of Task Manager; I gather that's what the "0" in there must stand for, right?...).
(For reference, further reading about this "Image File Execution Options" registry key for example
here.)
Could it by any chance be that your case is any way similar, melissamc212? Could you please check in your registry whether such key eventually exists and what value corresponds to it? You mention that Task Manager hasn't been working for months, so that may perhaps be some leftover trace from some old infection?...
Anyway, by then, the way I came to try and fix that "hijacking" of Task Manager was to sort of "hijack" it back. I suppose that was a strike of luck, as I didn't really know by then that my fix attempt would have a direct "cause-effect" result, but in the end it did and it worked for the result I hopped, so I got happy anyway.

So, what I did was to use
Sysinternals Process Explorer and set it to replace Task Manager (under Options > Replace Task Manager). As I say, I didn't know it by then, but afterwards I could notice that, when choosing this option in Process Explorer, what it does is to exactly use the "Image File Execution Options" registry key to set Process Explorer to be executed when Task Manager is invoked (such as from CTRL+ALT+DEL). So, in the end, what it did in fact was clearing that bad value which was created by the infection and which was preventing the execution of Task Manager,
"Debugger"="0", as it replaced that with the corresponding value for executing Process Explorer instead.
Just to add it as example, this is that same "Image File Execution Options" key exported from our registry here, when I have that option turned on on Process Explorer, i.e. have it set to replace Task Manager:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe]
"Debugger"="\"C:\\UTILITIES\\PROCESS EXPLORER\\PROCEXP.EXE\""
Ok, so, next then I set Process Explorer to restore Task Manager (again, under Options > now, Restore Task Manager). And so I had Task Manager back to being executed from CTRL+ALT+DEL.
I wonder, thus, whether in the end this info may be in any way helpful?...
Edited by DeLuk, 24 September 2009 - 07:52 PM.