A new type of rootkit has recently been seen. While most modern rootkits use the MBR and unused sectors of a harddrive, this one also misuses NTFS metadata to inject malicious code into a running OS.

Full article: http://www.securelist.com/en/blog/517/Cybercriminals_switch_from_MBR_to_NTFS

In case of an infection with phony anti-spyware software (such as Anti Spyware 2009), where the EXE file association has been corrupted, use these Registry fixes to reset them to default behaviour.

Notice

Be sure to select the right file for your system. XP, Vista and 7 all have different settings.

 

The latest trend in virii is the use of MBR rootkits to settle themselves in the unused (hidden) sectors of your harddrive, safe from any formatting or reinstallation of Windows. They cannot be removed by an antivirus as the rootkit directly interacts with the kernel upon boot, long before any antivirus system drivers are being loaded. The rootkit does not patch actual files or drivers, but rather does this dynamically upon booting Windows. A complete format of your system would not get rid of the MBR as it is hosted in the first sectors of your hard drive and therefore survive a format   ...

Currently, the official Avast for Mac Edition available for download is still at version 2.74, released somewhere in 2007.
This version still has many annoyances and bugs that have not yet been resolved (one of these issues is the ability to run automatically in the background, without the main window popping up at start up each time).

Luckily, the Avast Forum has a post, providing a new release candidate is available for download for some time now. The build is also a bit outdated but has at least many fixes that aren't present in the official release.

The direct download link   ...

Had a problem with an XP (SP2) computer and Avast Internet Security. Upon installing the product (and its subsequent reboot), the computer freezes right after startup. The mouse still moves, but keyboard does not respond, no applications get started.

After a search on the Avast forum, I came across this post, claiming there's a problem with certain applications and Avast on XP:

Quote

This is caused by a bug in Windows XP function ImageEnumerateCertificates( ) which is being called by firewall service when a process tries to access the net. This function (unpatched in all version of XP) hang  ...