Can't install Avast

I use Seven and when I try to install Avast it say to me : “You can install avast! only on Windows 2000 with Service Pack 4 or higher.”

03.10.2010 15:51:46 general: Started: 03.10.2010, 15:51:46
03.10.2010 15:51:46 general: Running setup_ais-2a5 (677)
03.10.2010 15:51:46 system: Operating system: Windows 7 ver 6.1, build 7068, sp 0.0 SERVER
03.10.2010 15:51:46 system: Memory: 58% load. Phys:432300/1038520K free, Page:1461272/2087096K free, Virt:2041520/2097024K free
03.10.2010 15:51:46 system: Computer WinName: NICO-PC
03.10.2010 15:51:46 system: Windows Net User: Nico-PC\Nico
03.10.2010 15:51:47 general: Cmdline: /sfx /sfxstorage “C:\Users\Nico\AppData\Local\Temp_av_sfx.tm~a03516” /srcpath “C:\Users\Nico\DOWNLO~1” /sfxname “setup_av_free_fre”
03.10.2010 15:51:47 general: DldSrc set to sfx
03.10.2010 15:51:47 general: Old version: ffffffff (-1)
03.10.2010 15:51:47 registry: Deleted registry: Software\Alwil Software\Avast\5.0\UpdateReady
03.10.2010 15:51:47 general: Install check: SetupVersion does NOT exist
03.10.2010 15:51:47 general: SGW32AIS::CheckIfInstalled set m_bAlreadyInstalled to 0
03.10.2010 15:51:47 registry: Get registry: Software\Microsoft\Internet Explorer\Version=8.0.7068.0
03.10.2010 15:51:47 general: Error:Your operating system does not meet the minimum requirements. You can install avast! only on Windows 2000 with Service Pack 4 or higher.

Any ideas ?

what’s your exact OS version?
avast can’t be installed on Windows server edition - and your pre-RTM versions (build 7068) may cause some troubles, because avast hooks some internal OS functions and I know they changed some addresses between beta and rtm versions (that’s why sandbox will not evan start, etc).