Are you running Windows 8? I am, and I had the same problem. My Windows 7 computer did not have the same problem. Regardless, I fixed it by doing the following:
- Open a new tab
- Enter the following URL in the address bar: chrome://flags
- Scroll down until you find "Enable New Dialog Style"
- Disable it (will go from white background to grey background)
- Click the "Relaunch Now" button at the bottom of the window
I like the new dialog style. Except for the whole "contents overflowing the window boundaries and thus being entirely useless" problem it seems to suffer from.
I think I enabled this option a couple of months ago and just forgot that I did it, because I've been having this problem for a while. I was able to deal with it until I tried to log into my router's config page and couldn't see the User Name or Password inputs, did a Google search, found this question, and was spurred into action. Thank you for also having this problem and inspiring me to find a solution. :)
I hope this helps!
Here's a screen clipping of the option in the Chrome Flags page: