Hi Rharv

I can only really describe it a faint click, certainly not loud but it's deffinately there and only seems to occur about once every couple of minutes so when I try to do a mix it happens once or twice in defferent parts of the recording. Thanks for your suggestions, having considered them, it could be interference from the mains but I've used the pc in different buildings and it's just the same. I think it's more likely that you're correct in thinking this is could be caused by some sort of update on the pc so it might just be a case of finding out what it is and turning off the update. I'm now using Vista, certainly never had this with previous pc and XP.

Gram