From: s|b on
Like the name says: it's an antivirus program and it's free.

| Most notable improvements include:
| - scanning and virus chest features now accessible even from Windows Safe Mode
| - aswSP.sys: solved a minor stability issue (fixed duplicating of protected handles)
| - Pro AV / IS: solved file enumeration problem on FAT32 partitions
| - enhanced compatibility with various Winsock LSPs
| - various improvements in the avast! sandbox
| - improved cleaning of file infecting viruses
| - added compatibility with screen readers; avast! should now be reasonably accessible to visually impaired users
| - system files imported to the virus chest after upgrade from v4.8 are now removed
| - IS firewall: solved a problem related to VPN connections (Windows XP)
| - IS firewall: solved a problem related to Xbox360 media sharing
| - IS firewall: solved a potential BSOD condition when changing logical drive mappings
| - IS firewall: solved a potential crash when saving the packet rules
| - IS firewall: fixes for Internet Connection Sharing
| - IS firewall: Windows 2000 compatibility
| - IS firewall: solved a compatibility problem with Logitech Desktop Manager
| - Pro AV / IS: solved a compatibility problem with PerfectDisk 11
| - Pro AV / IS: ashCmd.exe switch /@ should work again
| - Pro AV / IS: solved a compatibility issue with Acronis True Image
| - various fixes in the Outlook antispam add-in
| - fixes in ashUpd.exe
| - minor improvements in the installer, especially when upgrading from avast v4.8
| - avast! Screen saver can be now configured via the screensaver properties dialog
| - minor fixes in the GUI
| - added Dutch, Portuguese (Portugal), Norwegian, Finnish, Slovenian, Turkish and Vietnamese language packs

Download:
<http://www.avast.com/free-antivirus-download>

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s|b