It sounds like you stopped a process mid stream and the computer didn't like it.
I suggest you use the OS X disk and use it to start up the Mac.
Insert the Disk, restart the Mac and immediately hold down the C key.
When it start up, select the language and then go to the Menu and select Disk Utility.
Have Disk Utility repair the drive. When that is done have it run it by one more time to make sure it finds all the problems, then have it repair permissions.
When done, restart the computer and see how it is. Any better?
p.s. sorry for the delay in responding.