problem with wordpress 2.7 and error in my blog

Try uploading the files again. Some information probably got lost when FTPing.
I had the same problem with update.php and fixed it by uploading and overwriting just the core files in the root (not wp-admin, wp-content, and wp-include directories).

hi
i had this same error code:
Warning: array_keys() [function.array-keys]: The first argument should be an array in [mysiteaddress]/wp-includes/widgets.php on line 1044

here’s how i fixed it:
1.went to my cpanel
2.then to myphpadmin (i’d never altered this, so i was a bit apprehensive…but it worked)
3.on the left side list i found my wordpress data base & clicked it
4.with new choices on left side, i found wp_options,clicked once
5.in main window, clicked the browse tab, and looked for widget_text (there are many pages to choose from,so if you don’t see it immed.just use the dropdown menu to select the next page)
6.once you find the line with widget_text, hit the edit button (mine looks like a pencil)
7.when the new window pops up, you will notice a box with text that you added for the widgets. Delete all of the text in the box.
8.you will see a box underneath, that gives the option to save,then press go.
9.now a new page shows you the code which has been altered. you will notice at the very end of the sql code it says something like text=1, change it to a higher number to avoid this same prob in the future.
10.press save again
11.done

i hope this helps!