ME is prone to such behaviour.
Boot up go to START > RUN > msconfig
go to the START UP tab and remove all check marks by programs that load on startup, then re-boot and see what happens. I had an ME computer the other day doing exactly what you describe and this sorted it out. If all seems well, go back to MSCONFIG and just emable what you need (virus scanner etc) and see what happens.
On the IDE devices, rather than use Cable Select, set them to actual MASTER and SLAVE. Sometimes when CS is selected it can take ages, and hang, when detecting IDE devices.
EA