Experiencing the same problem, but have a slightly alternate scenario. In my case, I'd like to keep Track view on primary screen and Mixer + other floating windows on secondary screen. But similar christophe_t's case, I too get all floating windows stacked to the center of the primary screen when starting Reaper. From here, they all need to be moved to secondary screen each time. Might not sound like a biggie, but annoying as hell if you need to restart Reaper many times during a session. Eg. in my use, video clips seem to cause lot of hang ups that require killing Reaper process, and so I end up manually moving these windows quite a lot. When I was still running Reaper V3.x on WinXP, I never had this problem (floating window positions were saved/restored). Hard to say whether this problem has to with either Reaper V4.x, Win7 64bit or the combination of both. If anyone can confirm this behaviour on alternate versions (eg. Reaper V3.x or Win7 32bit), please do so.