Please help - strange plotting errors with very simple code

When trying to make very simple plots in R, very strange plots show up.
I'm not really sure how to describe the problem. I have only used R for about 2 months for my statistics class, but my final is on Monday and I can't study because no plots are showing up correctly. Sometimes it will just stop happening if I run enough code, but this time it is not.
There is not necessarily an error message, but it does say "plot (lm(cty~displ, cars))
Hit to see next plot: "
I uninstalled and reinstalled R

cars = read.csv('mpg.csv')
mode=lm(cty~displ, cars)
plot (lm(cty~displ, cars))

please note that this happens even if I put plot(mode) instead of plot (lm(cty~displ, cars))

If I click ctrl+enter a couple more times, then the graph will change to something even stranger.

It is normal to get four plots when you plot a model from lm(). You get Residuals vs Fitted, Normal Q-Q, Scale - Location, Residuals vs Leverage. Click on the Console (lower left pane in your image) and press return to see each plot.
What where you expecting to get with your plot function?