I'm migrating my PE7 from an XP 32bit box to a new WIN7 64 bit box. I've opened Project files of 12 to 15 trackscreated on the old computer and opened them on my WIN7 box, BUT I get drop outs when I set to loop playback. It plays to the end of the loop but usually drops out when starting the loop the second time. My cakewalk program is in Drive C, projects and audio are stored in Drive E. I've set the drivers to Asio and my Delta 1010 is playback and recording master. I think I've got the latest drivers for the Delta 1010. I raised my buffers first to 512 then to 1024, which I think is too high. Anyhow, I'm stumped and hope some of you can point me to an old thread (I couldn't find one) or offer some helpful tips. Many thanks over the years to all who've made this such a helpful site!!!!

I doesn't matter how "new" the OS or computer. If you have not optimized it for audio then you will have dropouts. 
Run the DPCLAT meter and find out what's running in the background. 

http://www.thesycon.de/deu/latency_check.shtml

Check the Windows Task Manager to see what else is running in the background. A new computer is likely to have some crapware that you don't need. 

Is your C: drive a 7200 rpm or 5400 rpm drive? Are you running Sonar 32- or 64-bit? 

What is your Windows Experience Index? Start-Computer-Properties. That may point out where your bottleneck is. The Delta 1010 should not be a problem.