Files in Windows 7 suddenly stuck in read-only mode.

Up until about 3-4 days ago, I could run, edit, and save documents from a folder on my second hard drive just fine. Now, I can't edit a word doc/text file/excel file unless I run the editing program as administrator. I've found that it's because the main folder where all these files are located is stuck in read-only mode. I can save files that aren't in this folder just fine. I try to turn off read-only, and it goes through the motions, but the change doesn't take. There are fixes to this I've found, but they just seem like hacks. I was wondering if someone could explain why this is happening and maybe provide a solution.

This folder is shared over my private home network. Is that a factor? It never stopped me from being able to do stuff before, but maybe an update knocked something out of balance.

Tech Support Guy System Info Utility version 1.0.0.1
OS Version: Microsoft Windows 7 Home Premium , Service Pack 1, 64 bit
Processor: Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz, Intel64 Family 6 Model 58 Stepping 9
Processor Count: 4
RAM: 3982 Mb
Graphics Card: Intel(R) HD Graphics, 1799 Mb
Hard Drives: C: Total - 99020 MB, Free - 59977 MB; D: Total - 14999 MB, Free - 10005 MB; F: Total - 476929 MB, Free - 154610 MB;
Motherboard: MSI, H61M-P31/W8 (MS-7788), 1.0, To be filled by O.E.M.
Antivirus: avast! Antivirus, Updated and Enabled