My status on drive optimiser shows 4 drives. The first 3 optimise weekly with no problems. The fourth is called \?\Volume{7e0918..... and shows it requires optimising and is 57% fragmented but it will not analyse, defragment or optimise Help please - I'm sure it's what is slowing down my laptop but I can't fix it

Method 1:
Use the Disk Cleanup utility to reduce the number of unnecessary files on your drives, which can help your PC run faster. It can delete temporary files and system files, empty the Recycle Bin, and remove a variety of other items that you might no longer need.

Delete files using Disk Cleanup
http://windows.microsoft.com/en-in/windows/delete-files-using-disk-cleanup#delete-files-using-disk-cleanup=windows-8
If the issue still persists, then try method 2.

Method 2:
Check the drive for error, refer to section repair a drive from the below link:

Improve performance by optimizing your hard drive
http://windows.microsoft.com/en-US/windows-8/improve-performance-optimizing-hard-drive
Important: While performing chkdsk on the hard drive if any bad sectors are found on the hard drive when chkdsk tries to repair that sector if any data available on that might be lost.