Setup is a Roland XP80 connected to a Windows XP Pro PC through the
midi port on a SoundBlaster Audigy sound card.  MIDI sequencing
software is Cakewalk Pro 7.0.

The issue is that over time a lag develops between pressing a key on
the Roland and the sound heard on the speakers.  When I change the midi
device in Cakewalk, the lag time disappears, but begins to drift back
in.  By the end of a four-minute song it's noticeable - subtle, but
there.  After leaving the setup alone for 12 hours, the lag time is
several seconds.  The keyboard - if it is the keyboard - didn't used to
have this problem, so I'm wondering if maybe my three year old didn't
start pushing buttons and hit some setting that I can't find.
Anyone have any ideas?

 - Wm