Win 2000 Professional OS: Boot Error Loop

After deleting several old programs (using Add-Delete utility), my Windows 2000 Professional fails to complete either a warm or cold boot. After the Opening screen, I see an error message in a white box, orange border, that says, “Entering Sleep Mode.” After a few moments, it cycles back to the Windows opening screen, then cycling back to the error box. I can enter “Safe Mode,” but nothing looks amiss there, and attempts to switch promising settings do not solve the problem. I guess I deleted some critical “shared” subroutine? Any suggestions other than to do an OS reinstall?