Q: I have a mac pro and when I started it up all I got was a gray screen with a question mark in a file?

oh dear ! you DO have a problem. if you have Mountain Lion, reboot, and press command+R to get to the restore partition, if not, try and find the original install dvd, start up from that (I think you have to hold down the C key, but I'm not sure, it's probably changed by now) and run disk utility. If memory serves me right, that means your Mac can't find a boot drive to start up from.   If you have maybe mac warrior or drive genius that may help, but if the drive is truly toast, then there is nothing much else you can do

I hope you are able to backup your stuff

Best of luck to you

John B

Option boot and reset the startup disk control panel

did it crash or freeze or not shutdown properly? power went out?

Just means it could not find your default boot device.

Yes you want backup, repair, and do a Safe Boot (you always want to tell me about what when where why too)

TimeMachine 101

https://support.apple.com/kb/HT1427

http://www.apple.com/support/timemachine

Mac OS X & Mountain Lion Community

https://discussions.apple.com/community/mac_os

https://discussions.apple.com/community/mac_os/os_x_mountain_lion?view=discussio ns

Recovery Mode

http://support.apple.com/kb/HT4718

ExpressLane

https://expresslane.apple.com/

Startup Manager: How to select a startup volume

http://support.apple.com/kb/HT131

Troubleshooting: My computer won't turn on

https://support.apple.com/kb/TS1367

General purpose Mac troubleshooting guide:

Isolating issues in Mac OS X

Creating a temporary user to isolate user-specific problems:

Isolating an issue by using another user account

Identifying resource hogs and other tips:

Using Activity Monitor to read System Memory and determine how much RAM is being used

Starting the computer in "safe mode":

Mac OS X: What is Safe Boot, Safe Mode?

To identify potential hardware problems:

Apple Hardware Test

General Mac maintenance:

Tips to keep your Mac in top form

Mac OS X Help

http://www.apple.com/support/macbasics/

Isolating Issues in Mac OS

http://support.apple.com/kb/TS1388