Object "computername" contains other objects

If you try to delete computer object in AD, you might receive warning message that Object <computername> contains other objects. To see what that computer object contains select in View menu "Users,Contacts,Groups and Computers as containers" in Active Directory Users and Computers Console and you will be able to see what that computer object contains.

In most cases it will be a printer, if the computer object is client workstation.

"Internet Explorer has modified this page to help prevent coss-site scripting."

Internet explorer 9 includes cross-site scripting (XSS) filter which is enabled by default http://windows.microsoft.com/en-GB/internet-explorer/products/ie-9/features/cross-site-scripting-filter . In my case IE 9 was pushed via WSUS, and there were couple of older web applications still running, that IE9 was preventing from running properly thanks to the enabled XSS filter.
If you trust the application or it is running on intranet, and from some reason IE 9 is not applying local intranet zone settings, just add the link manually to the local intranet zone (local intranet zone has by default XSS filter disabled).

You can't deploy OS on client in SCCM 2007 SP2

If you try to install OS to the same client within one hour from the previous deployment, the machine will fail to boot into PXE. To fix this change the (HKLM\Software\Microsoft\SMS\PXE\CacheExpire value to for example 120 (2 minutes), 0 is presumed 60 minutes. For more info please check http://support.microsoft.com/kb/2019640 .