After Windows 8.1 x64 Professional is running for a while, when I go into disk management I get:

"unable to connect with virtual disk service"

Upon reboot it starts working again. I have done an sfc /scannow and it comes up with no errors.

Any suggestions?

This is more than a minor annoyance, when I connect a USB drive it's doesn't map a letter to it and I have to go into disk management to do so. Rebooting each time is costing lost productivity. 

Hi,

According to the error message, it seems like Virtual disk service problem. you can access to Service to check VDS service status, make sure it is running well.

If there is any problem with this service, please open Registry and navigate to the value below:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\vds

Check its permission, make sure its user: ALL APPLICATION PACAKAGES have Read permission.

Hi Roger,

Yes, it does have the read permission.

Have you tried to reinstall VHD driver in Disk Manager for test? if not, please have a try.