I normally copy my Outlook directory from my Desktop (Win 7) to my laptop (Win 8.1) and vice versa via a USB 3 backup drive and the process takes a few minutes but this time it is taking like a whole day.

As this is the only way I can keep both machines directories synced it's driving me mad - I have uninstalled Malwarebytes and closed down all security software and checked that ram is OK - any advice available.

Not sure why you are having issues today but I've used this

http://www.synchpst.com/

before for clients who want to synch their outlook datafiles.

Thanks - I don't want to spend the money - I had a look on Task manager and don't see any active processe athat could be slowing things down - it seems to get stuck on the data type files so I suspect some form of hidden security check but can't find out what it is.

If it's a single directory that you copy, I'd suggest using a DOS window, I find it's a little quicker and more reliable than the traditional Windows drag and drop.

The other thing I see slowing file transfers down is the number of files. Windows really doesn't like lots of small files, it seems to work much harder than a single file of the same size. I often use a zip file to transfer large numbers of small files.

Thanks for that - to clarify a bit more - the process has always taken around 2-3 minutes to copy around 10GB of data using Terracopy and selecting "only replace older files" but all of a sudden it froze - I uninstalled it and used the DOS process but the larger that 2GB bakup files and Outlook Data files are taking about 6 to 15 hours each instead of the normal few minutes.

Maybe it's some new update in Windows that is causing the problem.

Device drivers perhaps? That sort of speed is certainly within the realms of USB 3, but if something has messed them up then Windows might be dropping to USB 2 (or even 1!).

Might be worth deleting the drivers, connecting the drive and letting Windows refresh them?