Wordpress and PHP code plugin

Hello,
I have a blog. In my blog I have examples of code. For some reason when I use the editor and insert a

'

Code (markup):

it is printed in wordpress as a

‘

Code (markup):

Which obviously caused parsing issues when people copy and past the text for code such as:

echo ‘<a href="’.$links[$randnum].‘"><img style=" border:none" src="’.$images[$randnum].‘" /></a>’;

Code (markup):

should be:

echo '<a href="'.$links[$randnum].'"><img style=" border:none" src="'.$images[$randnum].'" /></a>';

Code (markup):

Any ideas as to how I can fix this?