ak500+ no connect to pc

[delltrotter]

I have a problem on 3 PC
when i open ak500+ it search com 1 than com 2.com 1.com 2
and don't see device
can somebody help me,or my device is dead?
it works on laptop who is dead,but it was before 7,8 months

Thanks

[delltrotter]

when i turn on device lamp is on and i hear beep once