Cannot change Visible in OnShow or OnHide
i am using Delphi 7. When the system times out, or if your computer goes to sleep and then comes back up the system gives an error: " Cannot change Visible in OnShow or OnHide." Can you please say reason of the error and Solutions 
Cannot change Visible in OnShow or OnHide
===

i am using Delphi 7. When the system times out, or if your computer goes to sleep and then comes back up the system gives an error: " Cannot change Visible in OnShow or OnHide." Can you please say reason of the error and Solutions 