Cannot defrag my computer since installing Windows 8.1?

Working for me too.  Right now Optimize is on Pass 7, 25% consolidated.  Has been running for a couple of hours.  (Interesting, the optimize drives dialogue is showing a process I started from the command line.)

This started with Norton 360, i.e., the error message and Fix Now not correcting anything.  15% fragmentation.  Seemed like system was getting slow.

After this is done will see if Norton defrag works.

Also have 23% fragmentation in \Volume{418bcc3b ... etc.}.  Will also see if I can get that one cleaned up.

Thanks for posting!

Same error code here.

You might have to be a bit more patient and wait for the update that was being referred to.

Windows 8.1 Update 1 to Be More like a Service Pack

http://news.softpedia.com/news/Windows-8-1-Update-1-to-Be-More-Like-a-Service-Pack-415856.shtml

See if you can isolate another cause for your problems.

What is your machine like in Safe Mode?  If it is OK maybe you can try a Clean Boot to isolate a cause.

How to start Windows 8 in Safe Mode

http://www.bleepingcomputer.com/tutorials/start-windows-8-in-safe-mode/

How to perform a clean boot in Windows

http://support.microsoft.com/kb/929135/en-au

How to perform a clean boot to troubleshoot a problem in Windows Vista, Windows 7, or Windows 8

http://support.microsoft.com/default.aspx/kb/929135

i got an update on my computer but its still doing the not defraging

There will be a big update in March or April and i hope they fix this and other issues.