Well, there's yer clue- if it didn't happen with different PC in same house... must be something in that system. Try one by one shutting down running services that aren't needed for recording.
Unplug the jack to the internet and see if there is a difference..
Turn off antivirus and antispyware
Turn off any 'monitor' software that may be polling the system looking for an iPod for something, etc.


I do not work here, but the benefits are still awesome
Make your sound your own!