Thought I would share my experience on this one.  I have a TASCAM US-1800 USB Audio I/O device and up to tonight haven't has any issues.  I brought up a sample CW project (Jodi Good - Where Did We Go Wrong). When I started playback, everything was fine and then all of a sudden, the tus1800u.sys file would start to disintegrate causing static, crackling, and eventually crash SONARPDR.exe. I disabled everything I could think of. Sometimes it would play one time through and then the second time would crash.  Also the tus1800u.sys file caused a BSOD.  The last thing I thought it would be was my disk defragmenting program  (diskeeper by Condusiv Technologies). I stopped the service and set it to manual.  No more issues!  

Good troubleshooting.  I'm taking a note of that service name, in case it comes up again.  Also, since you sorted it out, I'll mark this thread as Solved, just to avoid people thinking you're referencing issues with SONAR X2, specifically.  Thanks for the info!