ASIO driver problems - CPU straight to 100%

[Groovr]

The subject header pretty much covers it. I'm running PTLE 7.3 at home (for now), but my laptop is a little older & slower, so I'm looking to run a more basic DAW to record location stuff. Problem is, the second I switch over to the Digidesign ASIO driver, the CPU meter pegs to 100% and stays there until I close the host.

I'm on a Dell Inspiron 4150, Pentium M 1.8, 256MB RAM, Absolute fresh XP installation. I noticed the problem running Cockos REAPER, but it seems to be universal - I can replicate it in other hosts.

Before anyone talks about Pro Tools minimum system specs - I'm not trying to run PTLE here, just a reminder that I'm running a lightweight host which is well within the capabilities of my laptop. If I uninstall the Digi driver and switch to the laptop's on board audio (using Asio4all), it runs at about 2% CPU (about what I expected)

Any thoughts?