This is the step that no one wants to hear, but which needs to be said:

If you encounter mysterious failures when installing or running any of the tools in this tool kit (that is, Easy Cleaner,  CWShredder,  Sygate Personal Firewall, SpywareBlaster, GIANT AntiSpyware, Webroot Spy Sweeper, Spybot Search & Destroy, and Lavasoft Ad-Aware Personal), the safest procedure is to deinstall all of them, including your virus checker, and then reinstall all of the tools in this toolkit. (Reinstalling the virus checker is optional; I suggest doing an online check first instead.)

The rationale for such a drastic approach is that too often, such mysterious failures are the direct result of hardcore spyware that is trying to subvert the installation of tools that would otherwise find and delete them. This is especially true if GIANT AntiSpyware or Spybot Search & Destroy hang, since they seem to be the most frequently targeted by hardcore spyware.

If you do this second round, it is particularly important that you experiment with deinstalling your virus checker. I have seen a number of cases where the spyware was resident in the virus checker itself. Because virus checkers often have special privileges in the operating system, the result is that even in Safe mode, the spyware can still affect your system and prevent you from finding or deleting spyware.