Recently in the study ...
Long session, starting just after lunch ... tracking lead vocals, followed by the usual editing, a rough mix, then throw away some of the crap, re-record, fix, then ad libs ... Sonar working fine, despite vocals being tracked against a fairly plugin-heavy sub mix ...
2 minutes past midnight, during recording of some final ad libs, the odd audio drop-out game starts; hiking up audio buffers doesn't fix it, neither does re-syncing clocks, or even restarting Sonar ... it's late; time to call it quits; time for beer ... no worries about the project as the last backup is 10 min old ...
Next morning, no changes to the system, just a cold boot ... everything works fine at same settings. no further issues, neither when tracking nor mixing ...
no clue what caused that forced break; i can't really be Sonar or the project, as it worked fine again. some driver? maybe. probably not an update service, either; these are all disabled ... the world of win7 remains mysterious ...