I've seen this happen on a friend's Alienware PC. Just try doing a complete install (custom) again. It worked on my friend's pc. It's worth a try. Good luck.

Or else boot into OSX... go into Bootcamp assistant and erase your Bootcamp partition. Then create it again and install Win7 the way you installed Vista.
Yeah, I tried that just a bit ago. Still no go. First, I went into Boot Camp and erased and remade partition, Then retried loading Win 7 on it. When I got to the boot selection page it keep giving me a
Windows unable to install to the selected location Error: 0x80300024.Second, I searched the web and people were saying to take out the OSX HD and then it worked for them, just pop it back in after your done. Well, I did that things went good until I still couldn't get passed the
Setting up your computer for first use, I only got to that in safe mode. The computer would restart the last time and instead of loading back up it would just sit there black screen not doing anything. I let it sit forever and it would not load or do anything. At first the disc would spin, then It would stop and finally you wouldn't hear anything but the fans going. So, this time I deleted and reformatted on the Windows boot selection and got the same results. Third, I restarted again and it reloaded the disc, to the the beginning where it wants you to Install now. So, On the bottom I clicked repair computer, checked for fixes, All tests say its normal and that the OS booted fine!!!


I tried to load drivers from SL disc, maybe that was the problem, didn't work either. Put OSX drive back, held option key and It came up with the OSX HD and the Windows 7 HD. I clicked Windows and it did the same thing.
So, now Im back on the Mac side and can see that on the Windows HD there are 9.11 gb on it.
