hey there, ive been searching for an answer for my problem for a while now - and cant find a topic which involve my situation. so i figured ill describe what the steps which resulted in my problem. here goes. i like to have full control over my system (although it might help viruses exploit it) so i took ownership over my entire system drive using "takeown /f c:\ /r /d y" than added my user as admin to all my files "cacls c:\a /t /g USER:f" now everything seemed to worked fine until i wanted to install an app than i noticed that the Windows Installer service was down and i couldnt enable it apparently even more Microsoft services failed to load which i hadnt noticed - such as Windows Search service even an app im using to monitor network activities (CfosSpeed) failed to load the repeated error is mainly access denied (i looked through the event viewer->windows->system and found out about it) im not sure what permissions should i restore to my main drive - i imagine the %systemroot% is all messed up.. but it actually seem as if all the folder INSIDE %systemroot% are as they were pre-taking ownership - ie system,admin,trustedinstaller are all there. the c:\%systemroot% permission however were empty - ie all users authorized didnt had any permission set (not even read,exec) and even after adding to them - it didnt help i under stand that in %systemroot% the inheriting is different than any other plain folder - so ill hate to go through each file and edit it accordingly. well thats pretty much how it is, *not to self, taking ownership over c:\ - is a bad idea to say the least* thanks a bunch

Please try the steps in the following article to resolve the issue. The steps are also applied for Windows 7. "The Windows Installer Service Could Not Be Accessed" error message when you install a program in Windows XP Please note this part: Verify that the SYSTEM account has full control access permissions to the HKEY_CLASSES_ROOT hive in the Windows registry.Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.