Windows 7 won't open minimized windows, what could be the reason?

Question

Windows

Windows 7 X64 Enterprise.
With non-recurring periodicity, the following happens on the employee's computer: minimized windows and applications stop opening (neither by mouse click, nor via alt-tab), while new applications open in a maximized state (exactly until they are minimized), attachments cannot be viewed in the Outlook mail client, they cannot be selected (but the same attachments are selected with the shift button pressed).
Text cannot be selected, but the input focus is not lost, and characters can be entered and deleted from the keyboard. After a while, the symptoms described above may disappear. Restarting explorer.exe helps for a while.
I would be glad to any suggestions about the reasons for this behavior.

Answer 1

strange something. try changing the keyboard. maybe some key is stuck =)