To delete the corrupt file and have Windows recreate it do the following:
1. Double-click My Computer, and then click Folder Options on the Tools menu.
2. On the View tab, click to select Show hidden files and folders, and then click OK.
3. Delete any files in the “C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\S-1-5-18” folder.
4. Run the task scheduler and edit the broken tasks.
5. Re-enter the password for the user running each job.
If this doesn’t completely solve it, you will need to verify that the Protected Storage service is running and restart it.
6. Click Start.
7. Choose Run.
8. In the Run box, type services.msc.
9. Click OK.
10. Find the Protected Storage service, and right-click to select it.
11. Select Properties.
12. In the Startup Type list, verify that it is set to Automatic.
13. Click OK.
14. Restart the Protected Storage service by right-clicking and selecting Restart.
15. Redo steps 4 and 5 above.