I'm the other one who was having this problem and it sounds like it is indeed the exact same problem. Except that I have 98SE which is supposed to be supported by the G6 and as I pointed out in the other thread, this is not a USB problem as people keep saying, since the U-Disk Manager won't even write correctly to the hard drive. There's just some other incompatibility.
Anyway, StingX, if you bought the G6 to use for homebrew and GBA games, you can just use drag and drop through Windows Explorer. Then when you load up the G6, you can either go to the My Card section and select your game through that interface or--if you're willing to put a little more work in--you can use the nice G6 graphical interface, which just requires having the ROM in the right format, and an ICO icon file as well as save files (named *.0, *.1, *.2) all with the same filename as the ROM. There's a thread a bit down in this same forum that discusses the G6 icons and has downloads for a large collection of commercial game icons as well as a tool for making your own for the homebrew.
If it's DS ROMs that you want to use, you won't have so much luck. I've tried about 15 using drag and drop and while more than half of them have worked, the ones that didn't work were the bigger, better, nicer games that would be most worth pirating. Or perhaps you could just say that those are also the games that are most worth buying.
Otherwise, upgrade to XP or maybe Windows 2000, you should be able to obtain installations for those the same places you would get DS or GBA ROMs.
...word is bondage...