Some (if not all) of these links can help you alot when debugging a broken Windows installation.

• Dependency walker: this free program will show you an hierarchical view of dependencies (DLL’s needed, what these DLLs needs in return, etc) for a given program. You can also view the dependencies for a DLL file, an OCX file, and god knows what else. What’s cooler, you can “trap” a program so it runs inside Dependency Walker, so you can view in real time what DLL it needs at a certain point. There may be others features, but I haven’t messed around too much.
• DLL Help database: Directly from Microsoft, this database lets you search from a file name, from a package name (Like Microsoft .NET Framework), and you can see some basic stats (file size, date, where it came from). Handy when you’re not sure if the DLL’s installed in your system are the good one or some fake installed by a spyware. It would be safe to assume that only Microsoft products are listed in this database.
• Process Library: Lets you search with an executable filename (like iexplore.exe) and this site will explain where it comes from. Ideal to locate running spyware/trojans or to identify unknown running processes.
• Process Explorer: This, along with Process Library above, will give you as much information as possible on running applications. Process Explorer is one of the programs created by the guys from SysInternals (which is now part of Microsoft), and is a replacement for the task manager, except that its a task manager on steroids. Just like dependency walker, you can get information about dll’s used, subprocesses running, and you can even see what files, directories and even TCP/IP ports is opened by a program! You can set it so it completly replaces the Windows Task Manager: even if you try to run “taskmgr.exe”, Process explorer will be launched instead. Quick tip: Ctrl+Shift+Escape will launch Task Manager (or Process Explorer if it overrides Task Manager) from anywhere inside Windows. Some programs that tries to block user input like Ctrl+Alt+Del doesnt know about this keyboard shortcut, so this one works 99.9% of the time.

Happy(ier) Windows debugging!