Has anyone noticed the following?
Sometimes when I bring up the Help->Wolfram Documentation there is no text field to type into.
When I bring up Find and Replace there are two text fields for Find: and Replace with: but no other controls or buttons (No buttons Find Next, Find Previous, Replace etc). In this case on my system - win7-64 - the dialog box is unnaturally tall (whole height of screen).
Syntax highlighting seems somewhat erratic - defined symbols stay the wrong color for a while. Symbols that are part of a function signature, say f[x_]:=... stay the wrong color for a while as well.
Restarting Mathematica restores these.