Task Scheduler errors

Many of the recent posts describe problems I have had since November/December, 2005. Hacking and other root causes aside, mine were solved by changing ISP's and hard drives, and restoring a previous version of Windows. This last had to be done a few times and the symptoms lasted several months until I acted.

One of my remaining problems from the above mentioned is that task scheduler will not initialize a task. Norton System Works and anti-virus was compromised during the problem period, as well as other utilities.

Error messages are (were):

"General page initialization failed. The specific error is: 0x80090016: Keyset does not exist. "

In the task Properties window, no "start in" line is written. When "apply" is clicked, error is "no account name is specified. "

I have other error messages from the time before replacement of HD and reloading a previous state of the OS.

At the moment, the OS and other software are working well. How do I restore the task scheduler to operate?