Try deleting the cache associated with Safari.
Go to ~/Library/Caches/com.apple.Safari/Cache.db
Move that Cache.db file to the Trash.
Relaunch Safari to test. If that didn't help go back to ~/Library/Caches/com.apple.Safari
Move the Webpage Previews folder to the Trash.
Quit then relaunch Safari to test.
Maybe an extension or plugin issues...
From your Safari menu bar click Safari > Preferences then select the Extensions tab. If you have any installed, turn that OFF, quit then relaunch Safari to test.
If it's not an extensions issue, back to the menu bar click Safari > Preferences > Security.
Deselect: Enable plug ins. Quit then relaunch Safari to test.
If that helped, then you have one or more Safari add ons causing this.
Follow the instructions for troubleshooting plugins here > Safari: Unsupported third-party add-ons may cause Safari to unexpectedly quit or have performance issues
If it's not a plugin issue, go to ~/Library/Preferences. Move the com.apple.Safari.plist file from the Preferences folder to the Desktop.
Quit then relaunch Safari to test. If that helped, move the .pilst file to the Trash. If not, move it back to the Preferences folder.
edited by: cs
I did all you suggested. But the problem remains.
I find another interesting thing: for very very few webpages it can display in full height, like "http://store.apple.com/us", see below
the rest webpages remain displaying in half height of the window:
Same thing to other accounts. I found this problem long time ago, may be from the first time I used this laptop (MacBook Pro Mid 2010 i5). At first I thought this was normal and did not care about it. Do you think it is caused by the disk or Mac OS issues, since the problem exits when the laptop was new.
Thought I'd update the thread-
I posted this in the apple bug reporter (required me to get a developer account, which is really strange), but I don't think we'll see any solution. I noticed that many, many sites cannot be screencapped. The secured sites (email, amazon) don't work, of course. But other sites like Boing Boing won't ever work either - which doesn't make sense. Go figure.
This seems like a semi-broken feature that will probably see an update in the future, or be removed entirely.