Only COM19 was found.
But it don´t start.
It is no problem to start mining with the CPU.
What happens if you try to start it? Anything in the log then?
When I restart my computer then:
- maybe all of the 4 Singles are found, may be only a few ( let the devices connected )
- it is no problem if I do like this: start BitMinter, wait, connect the first BLF Single, wait, connect the second Single, wait ....
Sounds like the USB ports and/or devices are not functioning very well. I'll have a new version of the client out soon that lets you configure it to keep trying the same COM port over and over indefinitely. That could be useful in cases like this.