Ankef,
First thing to di is uninstall the unknown device. Go to device managers, right click the device, and click to uninstall it. AFter this go to this website and download the device named Chipset manager.
http://it.computers.toshiba-europe.com/cgi-bin/ToshibaCSG/download_driver_details.jsp?service=IT&selCategory=2&selFamily=2&selSeries=153&selProduct=624&language=13&selOS=all&selType=all&yearupload=&monthupload=&dayupload=&useDate=null&mode=allMachines&search=&action=search&macId=&country=9&selectedLanguage=13&type=all&page=1&ID=47461&OSID=10&driverLanguage=42
Install it then reinstall the Lan driver. This should make everything work. Look on the bottom of your notebook, and find out if your A100 is SAA9, SAA2 or SAA4. And make sure you download the appropriate drivers for your model, because A100-SAA9 is different then A100-SAA4. Make sure you are downloading the correct drivers and all should work fine.