Hi Joshua, did you check the Kernel panic message? the kernel panic's we are experiencing is directly relating to the nvidia GPU. it will be something like this:
...
Kernel Extensions in backtrace:
com.apple.NVDAResman(7.0.2)[7E65ECA2-D3A1-35F8-B845-C975FB531E7E]@0xffffff7f808 b2000->0xffffff7f80b88fff
dependency: com.apple.iokit.IOPCIFamily(2.6.5)[95ABB490-3AB5-3D5E-9C21-67089A9AE6A1]@0xffff ff7f8083e000
dependency: com.apple.iokit.IONDRVSupport(2.3)[E99C8907-946D-3F1A-A261-4C0F2D5D0451]@0xffff ff7f808a0000
dependency: com.apple.iokit.IOGraphicsFamily(2.3)[897EB322-FD55-36D7-A68E-9E9C34A74A84]@0xf fffff7f80868000
com.apple.nvidia.nv50hal(7.0.2)[2E84958C-1EEC-316B-9F7A-68C368F83476]@0xffffff7 f80b89000->0xffffff7f80eaafff
dependency: com.apple.NVDAResman(7.0.2)[7E65ECA2-D3A1-35F8-B845-C975FB531E7E]@0xffffff7f808 b2000
com.apple.GeForce(7.0.2)[18E50F21-1E7F-3FFE-B298-7CD7A11879F8]@0xffffff7f817390 00->0xffffff7f817f5fff
dependency: com.apple.NVDAResman(7.0.2)[7E65ECA2-D3A1-35F8-B845-C975FB531E7E]@0xffffff7f808 b2000
dependency: com.apple.iokit.IONDRVSupport(2.3)[E99C8907-946D-3F1A-A261-4C0F2D5D0451]@0xffff ff7f808a0000
dependency: com.apple.iokit.IOPCIFamily(2.6.5)[95ABB490-3AB5-3D5E-9C21-67089A9AE6A1]@0xffff ff7f8083e000
dependency: com.apple.iokit.IOGraphicsFamily(2.3)[897EB322-FD55-36D7-A68E-9E9C34A74A84]@0xf fffff7f80868000
...
You had a kernel panic (resulting in the black screen) but its possibly from another source?
If you didn't get the kernel panic "report to apple" popup after rebooting then you can access your kernel panic logs here: /Library/Logs/DiagnosticReports/
Hope that helps