After a restart, my computer can't go into the graphical login, it shows the tumbleweed logo and then the logo disappears, leaves me a blank screen. I can switch to the other virtual terminals with alt+ctrl+fx, however, I can't run anything in the terminals, even I login as root. When I login as root, I can only use some commands like "ls" or "cat". The virtual terminal freezes immediately if I run other commands like "rm", "vi", or even "init 5". I can't end the process with ctrl+c. I try "startx", it returns "hostname: Name or service not known", and nothing else as output. I can return to prompt by pressing ctrl+c.

Could you please help me to identify the problem? If you need any info, please tell me.
Thank you very much.