I've added wpp tracing to a set of drivers. Tracing works for the most part.Here are the remaining issues: 1 )I want to be able to have a user enable tracing on her system without access to my .pdb file. 2) With every line of trace sent to traceview, I get the following line on the DebugView window:"Invalid parameter passed to C runtime function." 3) Just recently, for some trace messages I get, system time Message00\00\ 0-00:00:00:00 unknown(xx): GUID=XXXX-XXXX--XXX(No format information found.) even though i supplied the .pdb file that was correctly built.