@ northumbria61; until now no results, but I'll continue trying.
@ difarn; that can't be the problem.
As I explained already in my thread; it happens on both an internal and an external cardreader; they couldn't have the same tap failure on the same spot.
And it happened with CF ánd SDHC; two different slots in any reader.
The cards were seen in the external reader on another PC and a laptop.
It is obvious that it has to do with the problem of USB on that particular PC, not detecting the cards when put in a connected reader (the cardreader itself being perfectly detected).
Weird is the fact that both reader and card are detected when reader is connected with card already inserted!
The cardreaders are compliant with SDHC. Which is also evident since they read the SDHC card, except on that particular PC with the reader connected first. And the problem is the same wenn using CF-cards.
Conclusion; the USB system on that PC only is working weird; but what is the cause, and how do I get rid of it.
I checked the knowledge and Q&A site of ASUS on that board, but nothing about this problem. No new drivers available.