Gray Progress Bar Dring Startup

I called in and asked about a slowly running computer and Applecare suggested holding Option+Control+Shift+Power Button for 5-10 seconds and then releasing and then hold the shift button while powering on to go into safe mode. I did this on my macbook pro as he told me and decided to go ahead and do it on my imac and mac pro as well. It worked on the MBP and iMac but on the Mac Pro the computer came on when I held the first key combo and is taking a really long time (hours) to start up. I need the computer to work, for work... I tried just restarting the computer, unplugging it, etc but each time it has the gray progress bar and takes a really long time.

Any help? Of course I downloaded and updated to the newest operating system through mac app store so I dont have a start up disc...

Thanks,

jonathan