Hopefully I'm missing something obvious in the settings but when I'm using the editor the cursor never goes beyond halfway and then, despite the fact that I have word wrap on, the text shifts to the left (off the screen) and the cursor stays centered. This becomes a problem when I am selecting multiple lines of code and the screen is jumping left and right depending on the length of the current line the cursor falls on. Any help in fixing this would be great. Im running V.12 Build 375 on a windows xp.

Check your editor settings.
Tools/Preferences/Customization/Modify Options

I've enabled and disabled every option there and the cursor still stays centered and forces the text off the left hand side of the screen.

Did you select HTML/PHP Documents on the left hand side of Tools/Preferences/Customization/?