I seem to be having a issue myself, on a fresh install of v4.2.2, any image paths I try and change in stylevars, don't work, I get this in my error logs.
Code:
[Sun Oct 13 11:34:30 2013] [error] [client xx.xx.xx.xxx] File does not exist: /home/ozzmodz/public_html/500.shtml, referer: http://www.ozzmodz.com/admincp/stylevar.php?securitytoken=1381682058-adb9e5c85375859b568dfbfd4e9428d7294705c3&adminhash=c2004db9c9722a44c3dab65a44435a69&do=fetchstylevareditor&stylevarid[]=titleimage&dostyleid=1
--------------- Added [DATE]1381696127[/DATE] at [TIME]1381696127[/TIME] ---------------
Really strange, I tried it again, a few hours after loading the site, and now it works.