I'm having this same problem of a Disappearing and Reappearing Virus TI using the USB connection.
Hardware: Access Virus TI
Hardware OS: 5.0.8.00
Computer: Mac Pro running latest OS. Everything is up to date.
-Additional USB devices are attached via 2 USB Hubs.
This issue has been reported here:
Midi Input and outputs changing after short period of inactivity
mac osx - virus midi device disappears
Do we have any progress on fixing this issue?
The USB drivers are useless as Logic keeps going crazy when the "Number of MIDI Inputs has changed…"
Please help !
GS