How to fix an error in a file created in Illustrator

Does it help when you go to View > Show edges?

What kind of peripherals (mouse, tablet) are connected to your computer? Sometimes behavioral hiccups with tools can be due to various issues in a mouse or tablet. A battery in a wireless device could be failing, a graphics tablet driver may stop responding, a USB cable (or USB port) could be going bad or there could be a hardware conflict between two devices. Some issues can be solved simply by rebooting the computer.

If the problem is with Illustrator itself the first trouble-shooting step I would try is resetting the Illustrator Preferences file. You can do this within Adobe Illustrator by opening the Preferences dialog box at bottom of the Edit menu or pressing Ctrl+K. Under the General tab there is a "Reset Preferences" button visible. Restart Illustrator after clicking the button. Preferences can also be reset by holding the Alt+Control+Shift keys when launching Illustrator. Or they can be reset by manually deleting the AI Prefs file and forcing Illustrator to re-build it.

If resetting Illustrator Preferences doesn't work I would remove Illustrator, re-boot the computer system and the re-install the app.