I'm having two bits of "odd behavior" that may or may not be caused by a virus or malware:
1. When searching my computer using Search Everything (http://voidtools.com/), I find notepad(4).exe. The file cannot be run, renamed or deleted. It is not visible when looking through the C:\Windows\system32 folder. There are regular, functioning copies of notepad.exe in C:\Windows, C:\Windows\System32 and C:\Windows\SysWOW64, all of which work just fine.
2. Perhaps related is another problem. When right clicking on a file in the Downloads folder in Firefox and selecting "Open Containing Folder", I get the following error:
"This file does not have a program associated with it for performing this action. Please install a program or, if one is already installed, create an association in the Default Programs control panel."
This also happens when right clicking a file in the Start Menu/Documents and selecting "Open File Location". The dialog box is entitled "explorer.exe" instead of "firefox.exe", but is otherwise identical. This happens in any similar location that I have tried so far.
Oddly, if the folder containing the file is open in another window on my desktop, selecting "Open File Location" or "Open Containing Folder" shifts the focus to that window and highlights the program.
I followed many posted suggestions on this, most related to making sure the registry settings for folder and file associations are correct (e.g., http://www.winhelponline.com/blog/file-asso-fixes-for-windows-7/) without success.
Apologies in advance if these issues are outside the scope of combofix. Looking forward to your reply. Thank you!