I have had quite a bit of trouble installing NOD32 on a friends machine. The story may be long, but here goes. This 5 year old dell is running Windows Home SP2 ( an update from the original SP1 installation ). The machine was running a recently updated Mcafee suite - 2007 I think - and had been running some form of Mcafee since the beginning. The owner also says something from EZtrust was also used for a time. I started by downloading the free-trial NOD32 onto this machine. I uninstalled Mcafee through the "add/remove programs" in the control panel, rebooted and verified there was no Mcafee processes running. I then installed NOD32 without errors and rebooted. Logging into windows took a long time, and when we finally got in there were two big problems. 1) We were logged in as the same user, but it looked as if this were a new user account. The OS had created new user folders under the "Documents and settings" of the form "oldusername"."computername". We were offered the standard "take a tour of XP" bubbles that you see on a new install. 2) The system was totally unstable, and after a bit of activity would freeze. So I got into safe mode, uninstalled NOD32, and restored to the previous day. Everything seems OK now, except for the lack of Anti virus software running. I then ran the Mcafee removal tool as suggessted just about everywhere. That when fine - no errors. We then reinstalled NOD32 without errors, but still had problems. Upon reboot and logging in the following things happened: 1) A warning that an exception was thrown by something with HP in its name. I assume it is the HP software that runs the USB printer. 2) NOD32 give an unable to update error just as described in the FAQ. http://www.wilderssecurity.com/showpost.php?p=863309 4) Opening Outlook gives a message about the .pst file already being in use and won't open. 5) Firefox complains about being unable to load or use its security features. 3) Restarting the computer hangs as windows tries to shut down. As for 2) I have gone through the list of possible reasons. There is plenty of disk space. The temp folders exist. They have the same permissions as my computer which is running NOD32 fine. And I have redownloaded the installation file and tried again. I have installed and uninstalled NOD32 about ten times using different accounts, in safe mode.... with no luck. Finally, there are a couple of things which may or may not be important. 1) The microsoft security center says that mcafee is running, even though it is not. 2) There is something a little bit screwy with the permissions on the user account. Windows says it has administrative privileges. However, using msconfig and applying changes gives a message about not having rights. I just press ok. It acts like the changes won't be made, but after rebooting we can see that the changes we wanted to make have in fact been made. Thanks for any and all help...My friend is considering reinstalling Mcafee...I hope I can figure this out before he loses patience.