itlogicsystems

Sorry about that...  I have zero experience with either device, but after doing a little research both devices do the same thing, both are reviewed pretty much the same.  So really it comes down to cost...  I'm not familiar with the british pound, but it appears on amazon the TP-Link TL-WA850RE is cheaper.  

The malfunctioning worries me.  Try the device in another computer & see if it malfunctions as it did it the first PC.  If so, then there is a very good chance there is something wrong with it.  If it doesn't malfunction, then it may be a driver issue.  Completely uninstall the drivers, reboot, then reinstall drivers, reboot again, then insert the usb wireless device & see what happens.  Post back, hope this helps!

It has been my experience that you cannot beat a wire when it comes to local or internet connectivity.  If I were you the only option I would be considering is a hard wired ethernet connection.  I'm not saying wifi is junk, because it is not, i'm just saying that a hard wired ethernet connection is better.  Hope this helps!