Very strange - I don't use aptitude in interactive mode - only cli mode - so I've never encountered anything like that. Were you running in a virtual terminal or in a main tty? Can you ping the hosts in your sources.list ok? Try the following:
Code:
aptitude clean
aptitude update
aptitude -f install
aptitude full-upgrade
Post any output.
Don't hard reset a frozen system, use "magic keys" first e.g:
ALT+SysRq+S
ALT+SysRq+U
ALT+SysRq+B
(google it)