It's a BIOS problem with USB handback I expect (do you have a Phoenix BIOS?) - 5.2.3+ has fixes for this situation, you can find out more from the product release notes.
Thank you for your prompt reply
I'll check the proposed solution...
all the best
I hate to tell people to upgrade, but in this case, I think you are one version too far behind - there were a lot of fixes for this BIOS bug in 5.2.3 which I expect might solve your issue.
Test without encryption enabled until you are sure it works - it's much simpler and faster to remove the product, and it makes no difference to this particular problem.
There is USB hadback control feature in EEPC 5.2.3 and up. This might resolve your issue.
Otherwise review your machine settings. Make sure that USB support is NOT enabled.
You may need to go through EEPC emergency boot and disable in Lenovo PC BIOS legacy USB support (as workarounds).