Wonder if your system gets to CPU intense and over heating to cause reboot. Can you leave the card in and not use it for that period of time or does it still reboot while not using it for video transfer? Also if worked fine in FC7 maybe the newer kernel is the cause. Either upgrade or downgrade the kernel and test it that way too.
Brian
Distribution: RHEL 5.1 with Pieces of this and that.
Kernel 2.6.23.9, KDE 3.5.8 and KDE 4.0 beta, Plus Development src.rpm, ATI fglrx64_7_1_0-8.433-1 rpm with 3D and DRI working.
Acer 5100-5840 with webcam, ati, sdcard reader, sound, atheros based wireless, all working. Only thing not working is the memory stick reader.