Occasionally different anti-virus products can interfere with SharePoint operations. The following is a list of suggested locations to exclude from your AV scanner. Remember, this is merely a suggestion, so use at your own risk!

1.  %PROGRAM FILES%\Common Files\Microsoft Shared\web server extensions\12
2.  %WINNT%\temp
3.  %PROGRAM FILES%\Microsoft Office Server
4.  %WINNT%\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\
5.  Documents and Settings\All Users\Application Data\Microsoft\SharePoint\Config\     (the config cache)
6.  %WINNT%\Temp\WebTempDir

UPDATE: We've released a KB that covers this.
http://support.microsoft.com/kb/952167