
Yeah.  Sounds typical.  Windows makes all sorts of extra demands on hardware,
and therefore your machine can't keep up with things.  Ever notice how when
acessing the floppies in Windows, everything else slows to a crawl?  I 
imagine your backup and evertyhing else that is running fights for CPU time,
and sometimes the backup program loses.  Be glad.  I can't even run in 
medium speed with CP backup on my machine, supposedly because I have a SCSI
machine which places extra demands on the data bus.