Cyclone III development board and USB FT245BL

Fortunately, you haven't been asked if the PC is powered at all.

Please consider, that the Altera support guy is apparently focussing on trivial user handling errors. He may have missed some details in your support request. However, as matter of fact, these trivial errors are happening as well, and I expect, that Altera support is dealing with a lot of it.

I don't want to excuse inattentive reading, but it may be necessary to express your intention more clearly for Altera suport. Generally, the question should be addressed to someone responsible for the design of Altera Development Kits.