Validate the lpt1....

I have this code :
---
Open "lpt1:" For Output As #1
For I = 1 To Pulsos
Print #1, Chr(Caracter)
Next I
Close #1
--
but if I send something when there's no printer conected to the lpt1 my computer no respond, and I need to restart it.

how can i to validate.

Why don't you use Printer.print instead of printing to lpt1?
It is just that printing to a port is old technology. It still there for backwards compatibility.