computer freezes when I try to reboot it.

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http://crunchbang.org – Hi,So a few days ago I installed #!11 on my sister's computer. Its her first time using any linux distro and shes loving it so far! I thought it might be challenging for her to start with openbox but she really likes it and thinks its simple and fun.The system worked well pretty much out of the box. There is only one issue which is that when she tries to reboot, the system freezes. I tried to also reboot from terminal and got the same result. The reboot sequence freezes on the bash screen where theres "<computer_name> login:" and its stuck on that. She owns an acer D255e. (HowTos)