My horizon has mucked up cus of the update can some one help me plz?

i need help cus my horizon has gone wrong when i try 2 mod it sez

“unhandled exception has occurred in your applcation. if you click continue, the applcation will ignore this error and attempt to continue. if you click quit, the applcation will close immediately.”

can someone tell me what to do plz.

and what does this mean

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.