HD activity causing audible noise thru speakers

This subject pops up now and again...
Using an M-Audio 2496, hearing hum in signal (I can solve this problem easy enough if its a ground loop..) but strangely also hearing chirps/clicks/squeals when hard drive activity is present.
Anyone crack this issue?
Have you found that the probable ground loop hum is related to the HD noise, or is that a separate interference issue
to be sloved?
The MB is a ASUS p4800 delux that previously worked flawlessly/clean as a whistle with an Echo layla 3g.
I might look at the power supply as a culprit too.  
Thanks in advance.