Cakewalk not reproducing consistant sound with Netbook running Windows 7

I have sonar home studio and use it for arranging songs
My question is - I use Cakewalk Express 8 to play my songs when I play out.  I know it is old but just like the layout and I am familiar with it. 
Exp 8 is running on a new Netbook (Windows 7) that feeds an Alesis synthizer to the PA.  When I play a song I use a 4 beat drum to signal me the song is starting.  With the old computer I got 4 beats (bass drum) thump thump...  With the new Netbook I get Thump tic thump tic.  Why is it not correctly producing thumps ?  All the note parameters are the same.  I can't figure it out!  Help?