i?ve read a lot about ff400 conflicts with win7 in this forum. i have to fight with it on my own. here are some of my experiences that can may be help to fix the problem.

after buying a hp hdx with quad core and win7 64 i have massive probs with sudden dropouts. under ableton 8.09 the playback suddenly stops. and dont come back.
this is also with the internal soundcard, not only with ff400. i thought that this is a ableton 64 bit problem. i?ve installed win7 32. but the same probs.
i?ve updated everything. no result. i?ve checked the latenzy. horrible! i?ve found the grafik driver from nvidia made some latenzy probs. and i?ve change the windows ff driver to old-alt. now the latenzys where much better. also with ableton playing 4 tracks at the same time they stood in green. well!  but suddenly , after one hour of playing, playback stopped. same procedere. pressing play again , on the wave grafik symbol, nothing happened. pressing play on the start button - yes there it comes, but only for seconds, than its gone. i was trying that a few times, and then it was runnung again. for around 20 minutes.
maybe a ableton problem. so i?ve tried cubase working on that machine. it was running for around 4 minutes with a 12 channel track without plug ins. than it suddenly stopped. no sound anymore.
the most interesting thing is, that this effekt comes with Aquvox high end usb gear, with rme ff400, and internal idt card.
the changes of the windows ff driver and the grafik driver took positiv effekt on all three soundcards. but didnt took the problem away.
my last option is, to try completely without grafik driver.
hp notebook hdx 18 1080i
nvidia 130m
4gb
quad core