I have two IBM ThinkPads, X41 tablet and Z60m running Windows Vista
Business installed in exactly the same procedure. Both have SD card
slots so I bought 2 SanDisk Extreme III 2.0GB SD cards setup for full
use on ReadyBoost as I wouldn't use these card slots for anything
else.

The X41 with the SD card works perfectly. BUT when I enable ReadyBoost
in the Z60m, the CPU starts running at 100% and the HDD light starts
to flash and the whole system becomes laggy.

If I disable ReadyBoost, the CPU returns to normal. I have changed
cards around and its not the cards. I have formatted both cards, no
change. I have reinstalled latest driver for SD Card Reader from IBM
and no change.

The issue is purely a ReadyBoost one...anyone had the same problem or
might know where I could have gone wrong?