Thanks and sorry for the late reply - I have been waiting for the glitch to re-appear so I can gather more info - but it is currently behaving itself! I will reply when the fault recurs. Certainly it's not power related, because my mouse dongle (not bluetooth) is connected to the same USB hub and is not affected by sleep.

Update: it happened this morning. I could still see the UB500 in device manager. It said it was working properly (but it wasn't!). When I looked at the power state in device manager, it said D2. I unplugged and replugged the UB500 and the keyboard starting working again. Power state went to D0. I have a pair of bluetooth phones already paired to the UB500 and these wouldn't work either when the PC woke from whichever sleep state it was in.

If your UB500 Bluetooth adapter is not waking from sleep mode properly, you can try the following troubleshooting steps: Update drivers: Ensure that you have the latest drivers installed for the UB500 Bluetooth adapter. Visit the manufacturer's website or use their software to download and install any available driver updates specifically for the UB500 model. Power management settings: Check the power management settings for the UB500 adapter in your operating system. Open the Device Manager, locate the UB500 Bluetooth adapter, right-click on it, and select "Properties." In the "Power Management" tab, make sure the option "Allow the computer to turn off this device to save power" is not enabled. Disabling this option ensures that the adapter remains active during sleep mode. USB power settings: Some computers have USB power settings that can affect the behavior of connected devices. Open the Power Options in your operating system and navigate to the advanced power settings. Look for USB power settings and ensure that the option to selectively suspend USB devices is disabled. This ensures that the USB port supplying power to the UB500 adapter remains active during sleep mode. Regards, Rachel Gomez

Thank you. There is no power management in the adaptor properties. I have turned off the option to selectively suspend USB devices and will see if this improves things.