Motu 828 Highpitchsound/driver Not Found, possible hardware prob.. not sure Options

[redember]

Hi i noticed there was a similar problem brought up in the past... but i'm hoping there maybe some updates....
i run logic 6.4.3 on G5 macosx 10.3.4 with a motu 828 (not mkII) with the latest driver dowloaded from their site.

all of a sudden one nite i got "core audio selected driver not found (-10202)" - ive reinstalled logic+the 6.4.3 update+the motu driver nothing worked. the next morning everything is as it has been for years but after few hours this highpitched sound cuts in from the motu hardware and the driver is 'not found' again and core audio is not functioning.
this has happened a few days running now. just now it appears that if i powerdown everything for longer than, say, 20 minutes its all working again until a few hours after that the highpitch sound thing again.

(this maybe just a coincendence-- but it first happened shortly after a NI guitar rig2 demo version ran out (with no warning-just loaded up a song and "guitar rig2 not found" came up - i tried to re-load the demo version which was probably dumb - but i didn't expect major repercussions from doing that) could this have caused a bug? i have since ordered the real version in the hope it might fix things.
i'm now thinking the motu828 has got some kind of erratic problem and needs to be replaced?

hope someone can help, i am totally freakin out as i have just stared a business doing advertising music and the deadline's are sooo tite!
regards,
Ewan

[redember]

i'm not sure what resetting the motu entails, if indeed the original 828 has that function?

i've since been able to get the unit working on my laptop, with no problems, so i 'think' i've ruled out hardware failure... which is one step closer

but my desktop G5 will run fine for 20-30 minutes now and then the motu will cut into the hihg pitch sound and motu ceases to be recognised, almost like clockwork. and then it wont work again at all for that day.
there' must be some malfunctioning antipiracy demo file or something fooling with the system (an uninformed guess)
i've run diskutility, onyx etc but it's obviously not finding the file/program in question, i fear wiping the entire hard disk or something will be the eventual outcome....

got any tips on folders that i can check for timed-out demo files and related documents??
i've searched the harddrive for any files with "guitar rig V1"(the presumed offender) in it but i'm sure there are others related to the demo but not obviously named.

i have someone coming over on wed, to have a look.

thanks for the reply!
ewan