Tentacleware: Software which when installed on your PC gets into just about every aspect of your operating system, causing problems with other applications, and even the OS itself.
Programs like AOL, Gator, RealPlayer, and Xupiter are good examples. Not to be confused with Spyware, Tentacleware is so entrenched in your OS its hard or nearly impossible to remove completely.
Sometimes the removal of Tentacleware itself causes problems, becuase it leaves holes in the OS where it replaced a DLL file with one of its own specialized ones.
"this freaking software has its tentacles wrapped around my PC"
"this tentacleware has my Windows by the shorts hairs, and I can't get rid of it"
is the tentacleware of the millenium