I have using older version of skype on my ubuntu 10.4, after upgrade skype version 4.3, it seems have a crash issue. So here is the solution , if you have similar problem.
Go to Your user directory Like /home/[Ubuntu user folder]/.Skype/
Usually .Skype directory is hidden.
Rename it like .Skype_temp and run skype again, It will works, and another .Skype directory will be created.
Now if you like to get the old chat history, copy the files from
/home/[Ubuntu user folder]/.Skype_temp/[Skype user account folder]/chatsync
to New .Skype Directory:
/home/[Ubuntu user folder]/.Skype/[Skype user account folder]/chatsync
This should solve the problem.