ubuntu - coruppted ?

in my ubuntu,
1. no window list is coming in panel, after adding to panel it does not show window list. but i can select windows for window selector.
2. window close X icon is not on the extreme right corner, it is 2" left from edge
3. i cant not take screen shot by print screen, it was working last week
4. no icon is displayed in menu from applications/ places/ system, only names are written. when i try to change theme following messege is displayed

The default theme schemas could not be found on your system. This means that you probably don't have metacity installed, or that your gconf is configured incorrectly.

[freebird]

do one thing.from a terminal with internet on:

:~$ apt-get install ubuntu-desktop

if the problem is with graphics card or not will depend.post ur gfx card name