Today my macbook froze while i was doing a software update, so i manually reset the computer. When i turned it back on it will turn white with the apple logo, and the revolving bars, but then just loads a blue screen. i have control of the mouse on the blank blue screen, but nothing else happens. any help would be great. thanks.

Couple things..

1. Trying booting while holding down the shift key after the startup bong, this will make the machine boot into safe mode.

2. Boot from the System DVD by holding the "c" key down on restart. After the language screen the the next screen should have a menu bar across the top. Select Utilities then Disk Utility. In DU, choose the internal hard drive and repair permissions and verify the disk and make repairs if necessary.

Let us know how it goes, and good luck!