driver :unknown device

[zezoelec71]

I have usb to serrial cable named "prolific"
first its driver was installed correctly and it works good .
after a few days , when I connect it to my labtop it appears :unknown device
and the driver goes wrong
I tried to identify it handly but windows says that I have the last driver for it .
and it doesn't work .
anyone can help me ?
thanks

 

[amu_cpln]

try changing usb port .. and/or uninstall an d reinstall prolific drivers
which windows OS are you using XP ?

 

[zezoelec71]

I tried all the ports
and un/reinstall prolific drivers
my wundows OS is seven .
but the wrong is still existed

 

[amu_cpln]

that could be a problem ..
prolific drivers have a problem with version .. some older chips donot work with newer versions

and let me verify the problem ..
do you mean you open device manager ( in system properties) and find - unknown device ?
in that case this could be a hardware problem ..
check for end to end continuity in the cable .. and dry solder at the IC or cable connector