This is my reply to a post in the MameWAH forum at MameWorld:
The IPac family of encoders has some issues, actually it's a Windows issue, when USB devices are added and removed. The IPac will sometimes loose it's programming and need reprogrammed each time you turn your PC, cabinet, on. I just went through this last evening after removing my LCD TopGun. Folow these instructions, from the Ultimarc website:
Problem:
(USB Only) Board appears not to work until WinIPAC is run every time. Yellow exclamation marks in Control Panel, Device Manager.
Solution:
This is a rare problem, and is caused by a registry error. It is suspected that this problem occurs if the board is regularly swapped from one USB port to another, or different board versions used on the same PC. Microsoft have been alerted to this problem. The fix involves registry editing, the usual caution should be observed.
Run regedit, and open Hkey_Local_Machine/System/CurrentControlSet/Enum/HID and delete the keys containing VID D209 Also Hkey_Local_Machine/System/CurrentControlSet/Enum/USB and delete the same keys. You might have to right-click and set permissions to do this. Unplug and re-connect the board.
There is a executable file to perform the above task but it never works for me.
I am guessing that since after reboot you have nothing in Notepad this is your issue. When you launch MaLa it is then programming the encoder.
Hope this helps,
John