Ishbane: SOLVED my behind.
It's the exact opposite for me, ALL popups are invisible until i tab out and back in. Every time.
Edit: The popups make no sound, the game is still running but nothing happens.
Win7x64, Intel E6320, 460 GTX, 4GB RAM
The solved flag is applied by the topic starter to whatever post they feel answered their question best. In this case, the best answer in the OP's opinion was to contact support directly, since at the time this was posted (over a year ago), GOG was still collecting info on the bug. In the absence of any other solution, that is still probably the best thing to do, if only to remind the support guys that this is still an unresolved issue for several people.