REWORKED POST:
mmm... that autorun file is a leftover from your MAfee; because you are running Avast now it is safe to delete it.
==Please copy the text in the box to a notepad [format/wordwrap unchecked] and save as showkey.bat, as type "all files", to your desktop; dclick it to run, then post the file C:\showkey.txt
reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Drive Icons" /s >C:\showkey.txt
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Drive Icons" /f
start C:\showkey.txt
If that notepad is not empty then the red cross problem may be solved [you may have to restart...]. Otherwise could you then do that Combofix run?