Please describe what you mean by 32bit vs 64bit? Like are you talking OS, Sonar version, synth/plugin version, etc?
Also... what version of Windows (including 32 or 64bit versions), what version of Sonar (including 32/64 bit version), what synth is causing the issue and provide some extra system specification details (CPU, RAM, HDD/SSD's, audio interface).
What driver mode are you using for Sonar (ASIO, WMD, etc)? Are you using Asio4All or onboard sound?
Just knocking out a few troubleshooting questions so you can get some help.
Cheers.