Mmm, you could check the fragmention status of the external drive - it might be a bit borked.
What file system does it use?
Check the 'Policies' on the drive - it will either be optimised for quick removal or optimised for performance. I leave mine on performance.
Does it boot faster into SafeMode?
If the drive works okay if you plug it in after Windows has booted then it rules out the cable/connections - but not necessarily the port. I assume you tried another USB port?
If it is a fragmentation issue, then you need PerfectDisk - there is bound to be a 30 day trial.
What file system does it use?
Check the 'Policies' on the drive - it will either be optimised for quick removal or optimised for performance. I leave mine on performance.
Does it boot faster into SafeMode?
If the drive works okay if you plug it in after Windows has booted then it rules out the cable/connections - but not necessarily the port. I assume you tried another USB port?
If it is a fragmentation issue, then you need PerfectDisk - there is bound to be a 30 day trial.