I recently formatted my computer and reinstalled the essentials (Microsoft Office, Symantic Anti-Virus, etc.).  However, somehow there was a problem with one of the installations, and I got the error message: Error 1719.  The Windows Installer Service could not be accessed.  You may be running in safe mode or Windows Installer may not be correctly installed.  I followed the first set of instructions on http://support.microsoft.com/?kbid=315346 , and afterwards, Windows Installer seemed to work.  However, while following those instructions, I ran REGEDIT, and even while using it, the program would randomly close.  Now, my anti-virus software just randomly closes (even while running in the System Tray), I try to run it and it closes itself.  Same with REGEDIT and other seemingly system-related programs.  Any help?