Windows Defender removal reinstall problem



Removed Defender using Add Remove in Cont panel.
Attempted reinstallation; stopped.
Error message: "Another installation is in progress. You must complete that
installation before continuing this one".
Search registy for "defender"; found it in numerous locations
Tried to run "windows installer clean up installation wizard" and "Error
1500. Another installation is in progress. you must complete that
installation before continuing this one."
Security: Symantic Endpoint Protection on Windows XP Pro, SP3


Try to remove it in Safe Mode with Revo Uninstaller (Free version), then run

Use the REVO uninstaller (fourth/last option). That way you are
certain to scrap all the registry entries - and Windows Defender have a lot.

Also, use REVO and remove Symantic Endpoint Protection (later you can
reinstall again)

Note, uncheck Yahoos Toolbar

Download the basic version via
The basic version does not contain the disgusted Toolbar


As always, you should make sure that you have got a working system restore
point before you run any test, download or install a new game, application,
or software update, you make changes to your computer.


SEP will keep the Windows Defender service from starting due to compatability
issues between the two applications.

Running the Windows Defender service on a computer with SEP installed is

At this time, you cannot run both Symantec Endpoint Protection and Microsoft
Windows Defender as it mistakes Symantec Endpoint Protection for malware. For
this reason, Microsoft Windows Defender is disabled when Symantec Endpoint
Protection is installed.

Bill Sanderson

Don't dig through the registry like that it'll only lead to eyestrain. Have
you rebooted? Is the SEP install new? As Engel says, you aren't going to
be able to use Windows Defender with SEP, but that's not the same issue as
this "installation in progress" issue--which should be fixable.

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question