Since you are running Snow Leopard, Hold down the C key after the Startup Sound with the Snow Leopard DVD in the drive. When it gets to the install screen, look up top and click on Utilities. Click on Disk Utility and when it opens, click on the hard drive in the left windows and on the Partition Tab. Change "Current" to 1 Partition and then click Options and be sure GUID Partition Table is checked. Then click Apply. When it's finished, exit the Disk utility and continue with the install.

It sounds like your OSX partition got damaged somehow while you were using Bootcamp or formatting the partition in Windows. It could have been your extremely large Windows partition that messed things up like was said already.

Keep us posted.

When you want to install Windows again I would suggest a partition no more than 1/2 the drive and when you get into the Windows installer and format the partition NTFS be SURE you have the Bootcamp Partition selected!