I'm assuming this is a hardware issue, but it only occurs when I run a full hard drive scan. Most of the help articles I've read suggest doing a full virus scan as a first step. Obviously that isn't working. Any suggestions? I know the c185 code likely points to the hard drive, if I'm not mistaken?
That's usually caused by hardware issues/failure. Try doing this - in Vista Start/Alll Programs/Accessories Right-click Command Prompt and click Run As Administrator, OK the UAC prompt and then type chkdsk /r and click Enter. It will demur saying to do it at next boot Y/N? Enter Y and click Enter and then reboot and let it complete. Check again for the issue.
If you have several different lettered volumes you can enter the volume letter you want like this: chkdsk C: /r (again with all the spaces).
If it continues we need more information - Vista - what? SP1, x86 or x64? How much memory do you have and have there been any other BSOD issues?