Connecting external HDD turns the PC Off

[raksrules]

I have a maxtor 80 GB external HDD. I tried connecting the same to my office PC (Acer) but it told me that the device is not installed properly and it wont show me the additional drive also. Also on connecting the PC would abruptly shut down.
But the same HDD when connected to another machine (DELL) it is working fine. This dell machine is i feel advanced than the Acer.
But the above stated problem is only with Acer Machines.

[sagargv]

is it possible that psu aint supplying enough power ?

[BBThumbHealer]

Maybe there's some conflict with ur USB Ports !