I remember from my windows 98 days that there was a something config that would pull up a box like task manager, and on one of the tabs, there was startup processes
You can just go to your system information in 98 then > tools > System Configuration.

This has been removed from 2000 and later though so you just run msconfig from the run prompt and select the startup tab.




Typing "taskmagr" does work from the run prompt in XP home.

or right click on the task bar and the third option from the bottom is task manager
or, open a command prompt and type taskmgr
or, browse to C:/Windows/System32/taskman
or, Create a notepad document, then type taskmgr.exe then save it as ????.bat. Double click it and taskmanager should open.
or, type C:\windows\system32\taskmgr.exe in to the address bar of Internet Explorer.
or, try CTL SFT ESC instead of CTL ALT DEL.

or, if it has been disabled for some reason, copy the following in to the run prompt:

REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /t REG_DWORD /d 0 /f

This adds a key to the registry that enables task manager (if you are allowed to change the registry that is)

If you have been restricted from editing the registry, try pasting the following in to the run prompt:
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f

Again, it may or may not work depending on how locked down the box is and the method used to disable access to the registry.

Or if you have absolutly no rights to do pretty much anything, try the following:

Right-click the Start button and choose Open. Double-click Programs, then double-click Startup. Choose Start, Search, For Files or Folder, type taskmgr.exe in the top box, enter your start-up drive in the 'Look in' box (for most people it will be c:\), and click Search Now. When you see the Task Manager program file listed in the Search Results window, right-drag it to your open Startup folder. When you release the mouse button, choose Create Shortcut(s) Here. Now right-click the new shortcut and choose Properties. Select the Shortcut tab and choose Minimized from the Run drop-down list. Click OK. To keep Task Manager out of your way when you don't need it, double-click the shortcut to launch it, and in the menu bar at the top of the Task Manager window, choose Options, Hide When Minimized.

Task Manager will now start invisibly, but you'll be able to open its window anytime by double-clicking the CPU-usage icon in the system tray.

Or, if that does not work open the schedule a task wizard from the system tools folder > add a scheduled task > if taskmgr in not in the list browse to the taskmgr in the Windows/system32 folder or if access to the Windows folder has been disabled just type the path in > then select "start when pc boots up"! - this should by-pass any restrictions (providing scheduled tasks has not been disabled)

If you cant open it after trying all of the above..........fond a big hammer and take your frustration out on the box!!!