Sound Glitches

[csiscs]

Arite chaps,had ongoing probs trying to get recording setup on pc,dedicated system to recording,the only other thing I do with it is play mp3s or instructional dvd as still learning guitar.

Using toneport UX1 and UX2 think they are usb 1.1,one night it works fine the next start getting clicks and dropouts when playing back mp3 or dvd until after minute or two the only sound coming through monitors is noise, no mp3 or dvd audio,same when I record but bit more random.
Same thing happens if I drag an mp3 into Guitar Tracks pro to jam along with.

Any ideas or more info I could give that could help with solution?.

Done Vista tweaks,tried adding pci usb card,disabled onboard sound network etc.various settings 16 bit 24 increased latency nothing seems to make much difference.