SDHC ReadyBoost Card Stops Boot Process ?

I have just installed a Integral 16 GB SDHC card and dedicated it to ReadyBoost. Windows default settings decided to only take about 4GB of it for ReadyBoost so the rest of it is available for general use. The problem is that after I shut down the computer and then re-booted with the card in place, the computer got stuck half way through the boot process and just stayed there. I shut down the machine, removed the card from the onboard reader, re-booted and all was fine again. What's going on ?

Thank you A Guy. I will try NTFS on my card, but the problem with the boot stall is my main concern. Having the card in place seems to be having the same effect as leaving a floppy disc in place when booting up. Is that normal ?

I have formated the card to NTFS and windows has now taken about 9GB of the 16GB available. I have ticked dedicate this device to ReadyBoost. In the BIOS my hard drive is first in the boot sequence but the card still makes the compuer stall at startup ?

It's not a PCI card it's just one of those small cards that fits into the multi card reader on the front of my machine. It's a Integral Ultima class 10 16GB giving up to 20MB/s. By stall I mean that it gets only part of the way through the boot process and stops with a black screen and a flashing underscore in the top left of the screen. If I insert the card after the computer has booted it does all the things that a card is meant to do ? I have not considered "Safe Mode" No drivers were suggested by on the card specifications on the blister pack it came in. I have been to the Integral web site and no drivers are suggested or seem to be available.

It's the only card I have at present.