Why is the Task Manager disabled?
There are two main reasons that this are disabled: malware and corporate policy. This page is only meant to help with the former, as bypassing the policy of your company is not legal and is violating that agreement. Malware often disables this common tool to prevent you from using it presumably for removing the malware.
How do I enable it?First, you will want to remove the malware that caused this. Scan your computer with whatever antimalware software that you have and maybe with a few of the free online scans (listed on the Helpful Links page). If that doesn't remove it properly, you may want to consider joining an online forum (some also listed on the Helpful Links page), reading their instructions, and posting a HijackThis log.
One the malware is removed, Kellys Korner XP has a REG file that that should enable the Task Manager
here.