Files in Macintosh HD bold and won't open

Take it back to the vendor. It's not only in warranty, but if it is defective you can have it replaced automatically within 14 days from date of purchase.

Reinstalling OS X Without Erasing the Drive

Boot to the Recovery HD: Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the main menu. Repair the Hard Drive and Permissions as follows.

When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Continue button.

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

Also see:

Reinstall OS X Without Erasing the Drive

OS X Yosemite- Reinstall OS X

Note: You will need an active Internet connection. I suggest using Ethernet

if possible because it is three times faster than wireless.

You can adjust the view options in Finder by using Command+J or clicking on "View" menu then "Show View Options" or by right-clicking or control-clicking in a Finder window and then select the "Show View Options" to bring up the dialog box that has all kinds of options for viewing the items that Finder shows. Here is an image of what this "Show View Options" shows on my MacBook (not Retina):

I wonder if retina systems also have a 'Bold' checkbox? Also Apple has changed the default system font from what's been used for years - used to be "Lucida Grande" and now it's "Helvetica Neue" which some people have some strong objections to - see http://gizmodo.com/designers-explain-why-apples-new-os-x-typeface-is-a-str-15851 23982 for an interesting discussion.

You might also try to set the "Increase Contrast" setting in System Preferences "Accessibility" pane -- see http://osxdaily.com/2014/10/22/increase-contrast-mac-os-x-yosemite/ for more info

Good luck...