Are you talking about the one on pin 17 or pin 20?

We were discussing the 3.3V supply; hence pin 17. That and the 5v supply will both need decoupling caps. I'd try what Prolific suggests (0.1uF very close to the relevant pins) in the first link. That link also indicates resistor positioning close to the pins is important, so circuit layout is obviously critical.

 

Thats what I was thinking too. I appreciate you confirming that. Do you think the ferrite (spelling may be off) beads are needed as well? Or is Prolific just suggesting these for a cleaner system?

And when they mean "very close", are we talking a few MM, I mean everything is close as it is, and they don't give a "maximum" distance, they just say close.

 

have you ever searched for help in the official cadsoft-forum? ( http://www.cadsoftusa.com/community/)
perhaps you will find help there, you also can talk to experts in their community.

but in my eyes its unbelievable not to find help in this forum