Help with Mac startup crisis

Hello everyone. I am having a problem with my relatively new MacBook pro 17' intel i7. When I start up the computer, a loading bar appears under the apple logo. When the bar is complete I get to the screen where I enter my password. After inputting my password, a white/grey screen flashes momentarily and I am taken back to the password input screen. Restarting has no effect and neither does clearing the PRAM. I tried to start in safe mode by holding the shift key at startup but the loading bar problem still occurred. Please help! It should be noted that I used bootcamp to partition my hard drive and install windows 7 and that operating system seems to be starting up just fine. Thanks again for any help.

Some additional information:
1. I am currently running Lion.
2. Problems started occuring after an update to my Windows 7 OS.
3. Every time I try to restart after my password/blank screen loop, the screen goes white and I have to force shut down. It may just be me being impatient but I seems to get stuck on that white screen when i try to restart.

 

Tried to install lion in place using the recovery hard drive but when I got to the point where you select which hard drive to install on, the Mac hard drive was not there only the bootcamp and recovery drives which were both locked.

 

Does anybody have any other ideas?