Windows software: software that runs on the Windows OS. Unless you've done something special, it will not run on any other OS, including OS X.
Third Party Software: software that isn't written by the vendor who created your OS, and isn't written by you. Windows software is by definition all third party software. Third party software includes software written for OS X as well.
On-Demand Scan: performed via the Sophos Anti-Virus App, includes the "Scan Local Drives" and "Custom Scan" options. It's on demand, because you have to click a button to start the scan.
On-Access Scan: performed in the background by the Intercheck process every time a file is opened for reading or writing. Any file stored locally on your computer will be scanned as appropriate prior to use if On-Access scanning is enabled. Note that content downloaded from the internet directly to active memory (ie: a javascript from a web page that goes right to your browser window without being cached to disk first) will NOT be scanned by either on-access or on-demand scans. As soon as it is cached to disk (which will be after it has run in your browser), it will be scanned.
If nothing was found in an on-demand scan, then you currently don't have anything on your system that Sophos detects as malicious. You may have undetected malware hiding somewhere, but from your earlier descriptions of your computer and computer use, I highly doubt that you do.
Windows software: software that runs on the Windows OS. Unless you've done something special, it will not run on any other OS, including OS X.
Third Party Software: software that isn't written by the vendor who created your OS, and isn't written by you. Windows software is by definition all third party software. Third party software includes software written for OS X as well.
On-Demand Scan: performed via the Sophos Anti-Virus App, includes the "Scan Local Drives" and "Custom Scan" options. It's on demand, because you have to click a button to start the scan.
On-Access Scan: performed in the background by the Intercheck process every time a file is opened for reading or writing. Any file stored locally on your computer will be scanned as appropriate prior to use if On-Access scanning is enabled. Note that content downloaded from the internet directly to active memory (ie: a javascript from a web page that goes right to your browser window without being cached to disk first) will NOT be scanned by either on-access or on-demand scans. As soon as it is cached to disk (which will be after it has run in your browser), it will be scanned.
If nothing was found in an on-demand scan, then you currently don't have anything on your system that Sophos detects as malicious. You may have undetected malware hiding somewhere, but from your earlier descriptions of your computer and computer use, I highly doubt that you do.