I have recently updated my AVG anti-virus definition and it detected Xilinx dynamically linked libraries (.dll) as "Downloader.Swizzor". This results in the following error:
"FATAL_ERROR:Portability:PortDynamicLib.c:358:1.27 - dll open of library <?> failed due to an unknown reason. Process will terminate. For more information on this error, please consult the Answers Database or open a WebCase with this project attached at http://www.xilinx.com/support."
This is a false-positive detection on behalf of AVG and other vendors, such as Symantec's SAV, that do not detect this file as being viral.
AVG has released an updated anti-virus definition, and the newest definition does not detect the Xilinx dynamically linked libraries as being viral. Please update to the latest anti-virus definition.
If you are unable to update to the latest anti-virus definition and are using a paid version of AVG, you can configure your resident shield to exclude Xilinx dll from scanning. If you are using a free version of AVG, there is no way to exclude files from scanning, and therefore, you must turn off resident shield until you are able to update to the latest anti-virus definition.
You must reinstall ISE if you have quarantined Xilinx dll. Confirm that either your virus definition has been updated or that you have AVG resident shield turned off so that AVG does not flag the dll as viral on installation.