I stumbled onto a resolution for this problem. In case others run into the same issue, here is what I did:
A hidden folder in OS X at
/private/var/folders/*/*C/ (the asterisks represent character strings that are unique to each OS X installation) contains a number of cache files. Mathematica reads one or more of the resources in this folder at startup, and if they become corrupted or missing the "kEINVALErr" error can occur. By forcing the system to rebuild these cache files, Mathematica will launch as expected.
To force a rebuild of the caches in this folder, open Terminal and type the following line, pressing enter afterward (please note: the asterisks are actually asterisks, as in, Shift-8 on your keyboard):
rm -rf /private/var/folders/*/*/C/*
Then restart the Mac (the system will not rebuild these caches unless it is rebooted). As KAI noted in a previous post, performing the procedures detailed at http://support.wolfram.com/kb/3382 isn't a bad idea, particularly the parts involving the re-installation and validation of Mathematica fonts.