Hi, and thank you for your question.
The built-in disk defragmenter in Windows 7 has been broken for a long time, and comes with lot of bugs/glitches; it often does not defrag the drive at all, especially when a drive has gotten very fragmented over a long period of time.
To get around this issue, you may download and use a FREE, light disk defrag utility using the following link:
http://www.piriform.com/defraggler (get the free version)
This utility should allow you to defrag your system drive just fine, and the results will show when you check back on the Windows disk defragmenter as well.
If you need more help, please use the Reply box below to continue our conversation.
Otherwise, kindly take a moment to rate my service by clicking on (and submit) one of the five stars at the top of this page. Thank you.
PS: Please do not accept any remote assistance offer (simply "X" it out) if it shows up on this page; it's sent out automatically by our site, and not by me. We do not need to do a remote session for your issue; if you have any questions or concerns, do reply back to me using the box below and I'll continue to assist further. Otherwise, a positive rating (at the top) would be much appreciated :) Thank you.