Hi,
Thank you for posting your query on Microsoft Community.
From your issue description, I understand that scroll bar/slide bar disappears after a few seconds.
To help you resolve this issue, Could you please answer the following questions.
- On the scroll bar, you need to perhaps tell us where you are in Windows 8?
- When you have this issue; are you somewhere on the Start screen or in a Windows 8 store-style app or are you somewhere on the Desktop side?
- Where are you missing the "scroll bar”?
Please answer these questions so that I can rectify your issue as soon as possible.