Mac Pro advice please!

This is my first mac, has been great no problems! but today when I opened it the login screen was up but would not let me log in, after 10 min or so I decided to do a hard shut down. When I powered it up the apple symbol came on and it just kept running. Also the computer seemed hotter than usual as well as the plug.
I have no idea what do to??
Any ideas, thanks

And this is a Mac Pro and not a laptop?

Boot from the system install disk and run Repair Disk and see what is reported.